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README
.:. PURE-FTPD .:. Documentation for version 1.0.52 ------------------------ BLURB ------------------------ Pure-FTPd is a fast, production-quality, standard-conformant FTP server, based upon Troll-FTPd. The server has been designed to be secure in default configuration, it has no known vulnerability, it is really trivial to set up and it is especially designed for modern kernels. It was successfully ported to Linux, FreeBSD, Dragonfly BSD, NetBSD, OpenBSD, OSX, AIX and more. Features include chroot()ed and/or virtual chroot()ed home directories, virtual domains, built-in 'ls', anti-warez system, configurable ports for passive downloads, FXP protocol, bandwidth throttling, ratios, LDAP / MySQL / PostgreSQL-based authentication, fortune files, Apache-like log files, fast standalone mode, text / HTML / XML real-time status report, virtual users, virtual quotas, privilege separation, TLS and more. ------------------------ WHO'S USING IT? ------------------------ Many people new to Unix are running Pure-FTPd because they find it easy to install. But that software is also used on embedded systems and highly loaded production servers, especially for hosting services. For large sites with centralized user management, Pure-FTPd provides flexible authentication schemes including SQL and LDAP backends, plus the ability to easily write new custom handlers in any language. ------------------------ COMPILATION ------------------------ In its current form, Pure-FTPd uses some OS-specific system calls. And although some portability work has been done in order to ease its port to other operating systems, only Linux FreeBSD, NetBSD, OpenBSD, ISOS, MirBSD, BSDi, DragonflyBSD, Darwin, Solaris, Tru64, Irix, AIX and HPUX are known to work, other operating systems may need some tweaks. With Linux, any modern distribution should be ok. * Step 1 (optional but recommended): Create a specific, unprivileged user and group called _pure-ftpd, without any valid shell. Don't use this for anything else, including FTP virtual users. groupadd _pure-ftpd useradd -g _pure-ftpd -d /var/empty -s /etc _pure-ftpd If having a user whose name begins with an underscore is a no-go for you, you can also call it pure-ftpd, without the underscore. * Step 2: If you have Cdialog or Xdialog installed on your system, try the following command to build and install Pure-FTPd: make -f Makefile.gui If you don't have Cdialog or if you prefer the conventional way, here it is: ./configure make install-strip Et voila! The software is now installed in /usr/local/sbin/pure-ftpd * Step 3: To launch the server, just type the following command: /usr/local/sbin/pure-ftpd & If you installed a binary package (RPM, SLP, Debian), maybe use the following command instead: /usr/sbin/pure-ftpd & Your server is ready. Just type 'ftp localhost' to test it. If you want to automatically run the server when the system boots, add the previous command to /etc/rc.d/rc.local or /etc/rc.d/boot.local . Don't forget the '&' sign. Note: To deinstall Pure-FTPd (no, do you really want to do this?), use: ./configure make uninstall ------------------------ ADVANCED COMPILATION ------------------------ The "./configure" script accepts some arguments you might want to add before the compilation: /-------------------- "--with-" switches --------------------/ --with-altlog: in addition to the syslog output, support logging into a specific file, in an alternative format. Currently, the CLF, Stats, W3C and xferlog formats are implemented. CLF (common log format) is the basic format produced by Apache, WebFS, Roxen and most web servers. These log files only record file transfers and they can feed web statistic software (Analog, Webalizer, etc.) to analyze the load of your FTP server. The Stats format is a special output format, designed for log file analysis software. The W3C format is a standard format parsed by most commercial log analyzers (all analyzers with support for IIS should deal with it) . Xferlog is the traditional format created by wu-ftpd. Check the -O option later in this documentation for additional info. --with-brokenrealpath: some Solaris versions have a broken realpath() implementation. If altlog and/or pure-uploadscript doesn't seem to work properly on your system, try to recompile with this switch. --with-tls: enable TLS support. Read README.TLS for more about this feature. --with-certfile=<file>: the file with the TLS certificate (see README.TLS). The default is /etc/ssl/private/pure-ftpd.pem . --with-cookie: display a fortune or a customized banner when a user logs in (see the '-F' option) . --with-diraliases: support directory aliases ("shortcuts" for the "cd" command) . Please read the appropriate section about this (further in this manual) . --with-everything: build a big server with almost all features turned on: altlog, cookies, throttling, ratios, ftpwho, upload script, virtual users (puredb), quotas, virtual hosts, directory aliases, external authentication, Bonjour and privilege separation. --with-extauth: compiles support for external authentication modules. Please read README.Authentication-Modules and the pure-authd(8) man page before enabling this feature. Most users don't need it. --with-ftpwho: support for the 'pure-ftpwho' command. Enabling this feature needs some extra memory. Better use it when the server is run in standalone mode. It can be way slower in inetd mode. --with-language=english --with-language=albanian --with-language=german --with-language=romanian --with-language=french --with-language=polish --with-language=spanish --with-language=danish --with-language=italian --with-language=brazilian-portuguese --with-language=slovak --with-language=dutch --with-language=korean --with-language=swedish --with-language=norwegian --with-language=russian --with-language=traditional-chinese --with-language=simplified-chinese --with-language=hungarian --with-language=catalan --with-language=czech: change the language of server messages. Default is english. If you want to contribute a translation, please translate the 'src/messages_en.h' file and send it to <j at pureftpd dot org> . --with-ldap: use the native LDAP directory support. When this option is enabled, system accounts can be bypassed. You need OpenLDAP to use that feature. If OpenLDAP is installed in a custom location, you can use the --with-ldap=<directory> syntax. See the README.LDAP file for more info about LDAP and Pure-FTPd. --with-minimal: to efficiently use features of modern FTP clients, Pure-FTPd implements the basics of the FTP protocol, with many extensions (SITE IDLE, SITE CHMOD, MLSD, ...) . Using the --with-minimal directive, these extensions won't be compiled in. Also, there will be no standalone server, no lookup for user/group names, no humor and no ASCII support. But the executable file size will be smaller than in a default installation. You need at least GCC 3.3 to compile with this option. Regular expressions are compiled in. If you still want to reduce the size, use --without-globbing in conjunction with --with-minimal. If you are building an embedded system, use this. In all other cases, to avoid complaints from customers (especially with Windows clients), forget this. --with-mysql: use the native MySQL support for users database. When this option is enabled, system accounts can be bypassed. MySQL client libraries should be installed to use that feature. If MySQL is installed in a custom location, you can use the --with-mysql=<directory> syntax. See the README.MySQL file for more info about MySQL and Pure-FTPd. --with-nonroot: set up a server that doesn't need root privileges to be started. Any regular user can run the server. It can be useful if you have a limited shell access to a non-dedicated hosting server. But some features will be disabled and passwords can only be checked via LDAP, SQL or PureDB. When virtual chroot is enabled, people will be restricted to the directory the server was started in. This is an insecure mode, designed for setting up very temporary servers by regular (non-root) users. Port 2121 will be listened by default in standalone mode. If you want to use the nonroot mode, you must compile and *install* the software (./configure --prefix=... && make install-strip) . /sbin, /bin and /man directories will be created in that prefix. But you must also add an /etc directory (readable and writeable by the user pure-ftpd will run as) . You can change the anonymous FTP root directory through an environment variable named FTP_ANON_DIR. --with-pam: use pluggable authentication modules. Don't use this option if your login/passwd pairs are always refused (but the real fix would be to fix your PAM configuration). You need to create a /etc/pam.d/pure-ftpd file to properly use the PAM authentication. The 'pam' directory contains an example of such a file. --with-paranoidmsg: favor paranoid messages over sysadmin-friendly messages. When this option is enabled, login failures will show the same message to the user, regardless of the source of the problem. Without this option, "Authentication failure" is displayed when this is a password problem and "Sorry, I can't trust you" is displayed when the user has been banned by the sysadmin. --with-peruserlimits: enable per-user concurrency limits. Avoid this on very loaded servers. --with-pgsql: use the native Postgres support for users database. When this option is enabled, system accounts can be bypassed. Postgres client libraries should be installed to use that feature. If Postgres is installed in a custom location, you can use the --with-pgsql=<directory> syntax. See the README.PGSQL file for more info about Postgres and Pure-FTPd. --with-probe-random-dev: Pure-FTPd uses /dev/urandom or /dev/random devices to provide hardly-predicable random numbers. Presence of these devices are usually probed at compile-time. If you want to compile a binary package on a host, then run it on another host, this option will enable the probe at run-time. This is useless on Linux and BSD systems, but it can be needed on Solaris and QNX. --with-puredb: support virtual users, ie. a local users database, independent of your system accounts. Please read the README.Virtual-Users file for more info about virtual users. --with-quotas: enable virtual quotas. With virtual quotas, you can restrict the maximal number of files a user can store in his account. You can also of course restrict the total size. See the "quotas" section later in this document. --with-ratios: support upload/download ratios, to please w4r3z fr34k2. --with-sysquotas: support system quotas (not Pure-FTPd's virtual quotas) . --with-throttling: support bandwidth throttling (see below). --with-uploadscript: since 0.98, Pure-FTPd has a nice feature regarding uploads. Any external program or script can be automatically called after a successful upload. It needs another program installed by the Pure-FTPd package, called 'pure-uploadscript'. Check the man page for more info about this. --with-virtualchroot: usually, when a user is chrooted (-A and -a options), it's impossible to go out of his home directory. Enabling that feature makes it possible: symbolic links are always followed, even if they are pointing to directories not located in the user's home directory. This is very useful for having shared directories (for instance, have a symbolic link to /var/incoming in every home directory) . This feature isn't enabled by default. --with-virtualhosts: support virtual hosting. It means that you can have different anonymouns FTP areas for each IP address. If your server has only one IP address, you don't need that feature. But if you have multiple IP addresses and if you want a client that connects to IP xxx to get the content of /etc/pure-ftpd/xxx/ instead of ~ftp/ , enable this option. And read the the "VIRTUAL SERVERS" section at the end of this file. --with-welcomemsg: read 'welcome.msg' files for compatibility with some other FTP servers. This is a security flaw (anonymous users may upload 'welcome.msg' files to add random banners) . Pure-ftpd uses '.banner' files by default. --with-boring: display boring "professionnal-looking" messages. --with-bonjour: enable Bonjour support on MacOS X (see the -v switch). --with-rfc2640: enable support for charset conversion. It adds a dependency over the iconv library and it requires a little more CPU time. See the -8 and -9 switches. --with-implicittls: build a FTPS server (TLS is implicitly enabled). The protocol is incompatible with FTP and listens to another port by default (port 990, ftps). Never enable this option unless you know what you're doing. /----------------------- "--without-" switches -----------------------/ --without-privsep: disable privilege separation (see notes about this later), not recommended. --without-ascii: does not support 7-bits transfers (ASCII) . If you have customers using Windows clients to send scripts and HTML files, don't use this option or they will yell at you. --without-capabilities: if the capabilities library (libcap) is found, Pure-FTPd will try to use it in order to enhance security. This option overrides the test to ignore the library. Try this if capabilities don't work properly on your system. libcap can be downloaded from ftp://ftp.kernel.org/pub/linux/libs/security/linux-privs/ . --without-globbing: don't include the globbing code. It reduces the memory footprint but regular expressions won't work any more (things like 'ls *.rpm') . Most people shouldn't use --without-globbing. Globbing is a nice feature. --without-humor: if you find what this option does without peeking at the source code, you're a lucky guy! --without-inetd: if you will always be running Pure-FTPd in standalone-mode, enabling this flag can save a few code bytes. Don't enable --without-inetd and --without-standalone, because it's impossible to run a server without one of them. These options aren't enabled on binary distributions of Pure-FTPd, so that both inetd-like and standalone mode are supported. --without-iplogging: don't log any IP address to protect confidentiality, especially for political servers. --without-nonalnum: paranoid file name checking: only allow basic alphanumeric characters. Never enable this switch blindly, or your customers will complain. --without-unicode: disallow non-latin characters. Recommended if you don't have special characters in file names. --without-sendfile: on Linux, Solaris, HPUX and FreeBSD kernels, Pure-FTPd tries to reduce the CPU/memory usage by using a special system call (sendfile) . It works very well with most filesystems. However, this optimization is not implemented for all filesystems in current kernels. Users reported that downloading files with Pure-FTPd failed with SMBFS (Samba) on FreeBSD and TmpFS and NTFS on Linux (the error reported by the server is "broken pipe" or "Error during write to data connection") . If you are planning to serve files from these filesystems, you have to use the --without-sendfile switch to enable a workaround. It was also reported that PA-Risc Linux systems need this flag. --without-shadow: ignore the shadow passwords, even though they are auto-detected. Usually a bad idea, unless you use PAM, LDAP or SQL. Pure-FTPd support expiration dates of shadow passwords (both for accounts and passwords) . --without-standalone: the FTP server can normally run in standalone-mode (without any super-server) . If you don't need that feature and if you want to save few code bytes, add this option. A super-server such as xinetd or tcpserver will be mandatory to run the service. But the standalone mode is the recommended mode of operation. --without-usernames: never outputs user and group names in directory listings, only UIDs and GIDs. It improves security and performances, but some people find this not user-friendly. /-------------- Other notes --------------/ Other traditional autoconf options are of course recognised, in particular: - "--prefix=" to change the installation prefix, that defaults to "/usr/local/" - "--sysconfdir=" to change the configuration files directory (defaults to "/etc" unless you specified a prefix with --prefix) - "--localstatedir=" to change the runtime files directory (defaults to "/var" even if you specified a prefix with --prefix) FYI, the binary RPM packages of Pure-FTPd are configured with the following command line: ./configure --with-everything --with-paranoidmsg --without-capabilities \ --with-virtualchroot RPM packages are also compiled with --without-pam to enhance their portability. ------------------------ STANDALONE INSTALLATION ------------------------ This is the recommended way to start the server. Unless you compiled the server with "--without-standalone", running the server is as easy as typing: /usr/local/sbin/pure-ftpd & In the following examples, we will assume that the 'pure-ftpd' file is located in /usr/local/sbin. This is the default if you compiled the server from the source code tarball. But as I said earlier in this document, if you installed a binary package (RPM, SLP, DEB, TGZ), the server maybe installed in /usr/sbin/. So just replace '/usr/local/sbin/pure-ftpd' with '/usr/sbin/pure-ftpd'. When the previous command is run, the server will listen for incoming connections on every interface, all IP addresses and the standard FTP port (21) . If your system has IPv6 addresses, they should work as well. Now, if you want to listen for an incoming connection on a non-standard port, just append '-S' and the port number: /usr/local/sbin/pure-ftpd -S 42 Service names are also allowed ('-S smtp' and the daemon will be accepting connections on the SMTP port (25) . Very uncommon, but we should please everybody anyway, even disturbed minds) . Now, what if your system has many IP addresses and you want the FTP server to be reachable on only one of these addresses, let's say 192.168.0.42? Just use the following command line: /usr/local/sbin/pure-ftpd -S 192.168.0.42, The final comma is important, don't forget it. Actually, it's a shorthand for: /usr/local/sbin/pure-ftpd -S 192.168.0.42,21 If you prefer host names over IP addresses, it's your choice: /usr/local/sbin/pure-ftpd -S ftp.example.com,21 IPv6 addresses are of course supported. With previous command lines, the server will run in the default configuration. Anonymous FTP logins will be allowed if there's a system account called 'ftp' and every user of your system will be able to access the FTP server using their regular login/password pair. If you need to tweak that default configuration, other command-lines options can be added. For instance: /usr/local/sbin/pure-ftpd -c 50 & or /usr/local/sbin/pure-ftpd -S ftp.example.com,21 -c 50 & And only 50 simultaneous connections will be allowed. To discover what options are available please jump to the 'OPTIONS' chapter below. If the server runs perfectly for you in standalone mode, you don't need to read the following chapter about super-servers. But read the options. '-m' and '-C' are recommended. '-D' is also a good choice if you (or your customers) use broken clients. Please read on. When you run 'ps auxw|grep pure-ftpd', the result looks like this: root 15211 0.1 0.3 1276 452 ? S 13:53 0:00 pure-ftpd [SERVER] root 15212 0.1 0.5 1340 672 ? S 13:54 0:00 pure-ftpd [IDLE] root 15214 0.0 0.5 1340 672 ? S 13:56 0:00 pure-ftpd [DOWNLOADING] [SERVER] is the main server. If you kill this process, the server will exit after the next connection. [IDLE] shows a client with no transfer activity. [DOWNLOADING] shows a client downloading a file. [UPLOADING] show a client uploading a file. For easy scripting, the file '/var/run/pure-ftpd.pid' is created and it always contains the PID of the main server process. If you want to stop the server, you can just kill the processes: pkill -x pure-ftpd Of course, don't use -9 unless the server is completely stuck. -9 doesn't let processes any chance to clean things up and should never be used except where there's absolutely nothing else to do. ------------------------ SUPER-SERVER INSTALLATION ------------------------ Pure-FTPd can also run with the help of a super-server, like telnet, wu-ftp, finger or Qmail. This is not recommended. If this is an option, start it in standalone mode instead. Using a super-server is usually slower than the standalone mode. But if you love tcpwrappers or built-in filtering abilities of your super-server, Pure-FTPd can cope with them. Unix has tons of super-servers: Inetd (the most common one), TCPserver, G2S, Xinetd, Rlinetd, ... Only the first three will be covered here, but integration with other super-servers should be painless. **** Usage with Inetd **** Important: if security matters for you, forget inetd. In the default configuration, inetd will stop a service after a high rate of connections to the same port. This creates an easy denial-of-service. Also, inetd doesn't have any concurrency limit. Bad guys can fill up your memory and your descriptor tables even if you are restricting the number of connections in pure-ftpd. Better use a modern replacement for inetd, or run pure-ftpd in standalone mode. 1) Check that inetd is up: ps auxw | grep inetd root 3699 0.0 0.3 1072 492 ? S 15:47 0:00 inetd 2) Edit /etc/inetd.conf and look for a line like: ftp stream tcp nowait root /usr/sbin/tcpd in.ftpd The line may also end with "proftpd" or "wuftpd", but it should start with "ftp stream tcp". 3) Replace that line with the following one: ftp stream tcp nowait root /usr/sbin/tcpd /usr/local/sbin/pure-ftpd If /usr/sbin/tcpd is missing on your system, try the following line instead: ftp stream tcp nowait root /usr/local/sbin/pure-ftpd pure-ftpd 4) Restart the inetd daemon: pkill -x -s HUP inetd If 'pkill' is missing on your system, try this: kill -HUP $(cat /var/run/inetd.pid) **** Usage with Xinetd **** Add the following entry to the /etc/xinetd.conf file: service ftp { socket_type = stream server = /usr/local/sbin/pure-ftpd protocol = tcp user = root wait = no disable = no } On Redhat systems, you can also put this in a /etc/xinetd.d/pure-ftpd file. Then, restart the server: pkill -x -s USR2 xinetd **** Usage with TCPserver **** TCPServer is part of the ucspi-tcp package by Dan Bernstein. The simplest way of running Pure-FTPd with TCPserver is the following command: tcpserver -DHRl0 0 21 /usr/local/bin/pure-ftpd & You can add that line to your system local startup scripts (usually /etc/rc.d/boot.local or /etc/rc.d/rc.local) . If it doesn't work, replace 'tcpserver' with its full path (eg. '/usr/local/bin/tcpserver') . ------------------------ OPTIONS ------------------------ The previous steps should be enough to get a running FTP server. But you can add some command-line arguments to change its behavior. These arguments have to be added after the pure-ftpd path in your super-server configuration. For instance, you want to add the '-s' and '-a 42' flags. Here are what the configuration lines will look like in your super-server: - Inetd: ftp stream tcp nowait root /usr/sbin/tcpd /usr/local/sbin/pure-ftpd -s -a42 or ftp stream tcp nowait root /usr/local/sbin/pure-ftpd pure-ftpd -s -a42 If you use Inetd, don't put space between options and arguments. e.g. use -a42 instead of -a 42 . Inetd has trouble dealing with a lot of options and with characters like ':' . - Xinetd: service ftp { socket_type = stream server = /usr/local/sbin/pure-ftpd server_args = -s -a 42 protocol = tcp user = root wait = no disable = no } - TCPserver: tcpserver -DHRl0 0 21 /usr/local/bin/pure-ftpd -s -a 42 & - G2S: { SERVICE ftp DESCRIPTION "Pure-FTPd" RUN /usr/local/sbin/pure-ftpd -s -a 42 } Users need a shell listed in /etc/shells to get restricted or unrestricted FTP access. Alternatively, you can give them "ftp" as a shell. Users with a "ftp" shell will be able to login through FTP only: no telnet, no SSH. And there's no need (and you shouldn't do so) for an "ftp" entry in /etc/shells. Here are the recognized switches: - '-0': when a file is uploaded and there is already a previous version of the file with the same name, the old file will neither get removed nor truncated. Upload will take place in a temporary file and once the upload is complete, the switch to the new version will be atomic. For instance, when a large PHP script is being uploaded, the web server will still serve the old version and immediately switch to the new one as soon as the full file will have been transferred. - '-1': log the PID of each session in syslog output. - '-2 <file>': when using TLS, set the path to the certificate file. - '-4': only listen to IPv4 connections. - '-6': don't listen to IPv4, only listen to IPv6. - '-a <gid>': authenticated users will be granted access to their home directory and nothing else (chroot) . This is especially useful for users without shell access, for instance, WWW-hosting services shared by several customers. Only member of group number <gid> will have unrestricted access to the whole filesystem. So add a "staff", "admin" or "ftpadmin" group and put your trusted users in. <gid> is a NUMERIC group number, not a group name. This feature is mainly designed for system users, not for virtual ones. Note: 'root' (uid 0) always has full filesystem access. If you want to chroot() everyone, but root, use the following flag: - '-A': chroot() everyone, but root. There's no such thing as a trusted group. '-A' and '-a <gid>' are mutually exclusive. - '-b': Ignore parts of RFC standards in order to deal with some totally broken FTP clients, or broken firewalls/NAT boxes. Also, non-dangling symbolic links are shown as real files/directories. EPSV is disabled. - '-B': Have the standalone server start in background (daemonization). - '-c <number of clients>': Allow a maximum of clients to be connected. For instance '-c 42' will limit access to simultaneous 42 clients. There is a 50 client limit by default. - '-C <max connection per ip>': Limit the number of simultaneous connections coming from the same IP address. This is yet another very effective way to prevent stupid denial of services and bandwidth starvation by a single user. It works only when the server is launched in standalone mode (if you use a super-server, it is supposed to do that) . If the server is launched with '-C 2', it doesn't mean that the total number of connections is limited to 2. But the same client, coming from the same machine (or at least the same IP), can't have more than two simultaneous connections. This feature needs some memory to track IP addresses, but it's recommended to use it. - '-d': Send various debugging messages to the syslog. Don't use this unless you really want to debug Pure-FTPd. Passwords aren't logged. Duplicate '-d' to log responses, too. - '-D': List files beginning with a dot ('.') even when the client doesn't append the '-a' option to the list command. A workaround for badly configured FTP clients. If you are a purist, don't enable this. If you provide hosting services and if you have lousy customers, enable this. - '-e': Only allow anonymous users. Use this on a public FTP site with no remote FTP access to real accounts. - '-E': Only allow authenticated users. Anonymous logins are prohibited. - '-f <facility>': Use that facility for syslog logging. It defaults to 'ftp' (or 'local2' if you got an obsolete libc without that facility). Logging can be disabled with '-f none' . - '-F <fortune file>': Display a fortune cookie on login. The sentence is a random extract from the text file <fortune file>. This text file should be formatted like standard "fortune" files (fortunes are separated by a '%' sign on a single line) . Pure-FTPd has to be compiled with support for cookies (--with-cookie). If you just want a simple banner displayed before the login prompt, add the name of any text file here. - '-g <pid file>': Change the location of the pid file when the server is run in standalone mode. The default is /var/run/pure-ftpd.pid . - '-G': Disallow renaming. - '-H': By default, fully-qualified host names are logged. To achieve this, DNS lookups are mandatory. The '-H' flag avoids host names resolution. ("213.41.14.252" will be logged instead of "www.toolinux.com") . It can significantly speed up connections and reduce bandwidth usage on busy servers. Use it especially on public FTP sites. Also, please note that without -H, host names are informative but shouldn't be trusted: no reverse mapping check is done to save DNS queries. - '-i': Disallow upload for anonymous users, whatever directory permissions are. This option is especially useful for virtual hosting, to avoid your users creating warez sites in their account. - '-I <timeout>': Change the maximum idle time. The timeout is in minutes and defaults to 15 minutes. Modern FTP clients are trying to fool timeouts by sending fake commands at regular interval. We disconnect these clients when they are idle for twice (because they are active anyway) the normal timeout. - '-j': If the home directory of a user doesn't exist, automatically create it. The newly created home directory belongs to the user and permissions are set according to the current directory mask. Only the home directory can be created (so /home/john/./public_html won't work, but /home/john will) . To avoid local attacks, the parent directory should never belong to an untrusted user. Also note that you must trust whoever manages the users databases, because with that feature, he'll be able to create/chown directories anywhere on the server's filesystem. - '-J <ciphers>': Sets the list of ciphers that will be accepted for TLS connections. - '-k <percentage>': Don't allow uploads if the partition is more than <percentage>% full. For instance, "-k 95" will ensure your disks will never get filled more than 95% by FTP. No need for the "percent" sign after the number. - '-K': Allow users to resume and upload files, but *NOT* to delete or rename them. Directories can be removed, but only if they are empty. However, overwriting existing files is still allowed (to support upload resume) . If you want to disable this too, add -r (--autorename) . - '-l <authentication>' or '-l <authentication>:<config file>': Adds a new rule to the authentication chain. Please read the "Authentication" section, later in this README file. It's an important section. - '-L <max files>:<max depth>': To avoid stupid denial-of-service attacks (or just CPU hogs), Pure-FTPd never displays more than 10000 files in response to an 'ls' command. Also, a recursive 'ls' (-R) never goes further than 5 subdirectories. You can increase/decrease those limits with the '-L' option. - '-m <cpu load>': Don't allow anonymous download if the load is above <cpu load> . A very efficient way to prevent overloading your server. Upload is still allowed, though. - '-M': Allow anonymous users to create directories. - '-n <max files>:<max size>': If the server has been compiled with support for virtual quotas, enforce these quota settings for all users (except members of the 'trusted' group) . <max size> is in Megabytes. See the "virtual quotas" section later in this document. - '-N': NAT mode. Force ACTIVE mode. If your FTP server is behind a NAT box that doesn't support applicative FTP proxying, or if you use port redirection without a transparent FTP proxy, use this. Well... the previous sentence isn't very clear. Okay: if your network looks like this: (FTP server)-------(NAT/masquerading gateway/router)------(Internet) and if you want people coming from the internet to have access to your FTP server, please try without this option first. If Netscape clients can connect without any problem, your NAT gateway rulez. If Netscape doesn't display directory listings, your NAT gateway sucks. Use '-N' as a workaround. - '-o': Write all uploaded files to '/var/run/pure-ftpd.upload.pipe' so that the 'pure-uploadscript' program can run. Don't enable that option if you don't actually use 'pure-uploadscript' otherwise pure-ftpd will hang waiting for pure-uploadscript to start. - '-O <format>:<log file>': Record all file transfers into a specific log file, in an alternative format. Currently, four formats are supported: CLF (Apache-like), Stats, W3C and xferlog. If you add '-O clf:/var/log/pureftpd.log' to your starting options, Pure-FTPd will log transfers in /var/log/pureftpd.log in a format similar to the Apache web server in default configuration. If you use '-O stats:/var/log/pureftpd.log' to your starting options, Pure-FTPd will create log files in a special format, designed for statistical reports. The Stats format is compact, more efficient and more accurate that CLF and the old broken "xferlog" format. The Stats format is: <date> <session id> <user> <ip> <U or D> <size> <duration> <file> <date> is a GMT timestamp (time()) and <session id> identifies the current session. <file> is unquoted, but it's always the last element of a log line. "U" means "Upload" and "D" means "Download". Warning: the session id is only designed for statistics purposes. While it's always an unique string in the real world, it's theoretically possible to have it non unique in very rare conditions. So don't rely on it for critical missions. A command called "pure-statsdecode" can be used to convert timestamps into human-readable dates. The W3C format is enabled with '-O w3c:/var/log/pureftpd.log' . For security purposes, the path must be absolute (eg. /var/log/pureftpd.log , not ../log/pureftpd.log) . If this log file is stored on a NFS volume, don't forget to start the lock manager (often called "lockd" or "rpc.lockd"). - '-p <first port>:<last port>': Use only ports in the range <first port> to <last port> inclusive for passive-mode downloads. This is especially useful if the server is behind a firewall without FTP connection tracking. Use high ports (40000-50000 for instance), where no regular server should be listening. - '-P <ip address or host name>': Force the specified IP address in reply to a PASV/EPSV command. If the server is behind a masquerading (NAT) box that doesn't properly handle stateful FTP masquerading, put the ip address of that box here. If you have a dynamic IP address, you can put the public host name of your gateway, that will be resolved every time a new client will connect. - '-q <upload ratio>:<download ratio>': Enable ratios for anonymous users. - '-Q <upload ratio>:<download ratio>': Enable ratios for everybody (anonymous and non-anonymous). Members of the root (0, something called 'wheel') have no ratio. - '-r': Never overwrite existing files. Uploading a file whose name already exists cause an automatic rename. Files are called xyz, xyz.1, xyz.2, xyz.3, etc. Tip: if you compile with 'make AUTORENAME_REVERSE_ORDER=1' , the naming convention will be reversed. Files will be called xyz, 1.xyz, 2.xyz, 3.xyz, etc. - '-R': Disallow users (even non-anonymous ones) usage of the CHMOD command. On hosting services, it may prevent newbies from making mistakes, like setting bad permissions on their home directory. Only root can use CHMOD when -R is enabled. - '-s': The "waReZ protection". Don't allow anonymous users to download files owned by "ftp" (generally, files uploaded by other anonymous users) . So that uploads have to be validated by a system administrator (chown to another user) before being available for download. - '-S [<ip address>,|<hostname>,] [<port>|<service name>]'. This option is only effective when the server is launched as a standalone server. Connections are accepted on the specified IP and port. IPv4 and IPv6 are supported. Numeric and fully-qualified host names are accepted. A service name (see /etc/services) can be used instead of a numeric port number. - '-T <bandwidth>' and '-t <bandwidth>': Enable bandwidth limitation (see below) . <bandwidth> is specified in kilobytes/seconds. To set up separate upload/download bandwidth, the [<upload>]:[<download>] syntax is supported. - '-u <uid>': Don't allow uids below <uid> to log in. '-u 1' denies access to root (safe), '-u 100' denies access to virtual accounts on most Linux distros. - '-U <umask for files>:<umask for dirs>': Change the file creation mask. The default is 133:022. If you want a new file uploaded by a user to only be readable by that user, use '-U 177:077'. If you want uploaded files to be executable, use 022:022 (files will be readable -but not writable- by other users) or 077:077 (files will only be executable and readable by their owner) . Please note that Pure-FTPd support the SITE CHMOD extension, so a user can change the permissions of his own files. - '-V <ip address>': Allow non-anonymous FTP access only on this specific local IP address. All other IP addresses are only anonymous. With that option, you can have routed IPs for public access and a local IP (like 10.x.x.x) for administration. You can also have a routable trusted IP protected by firewall rules and only that IP can be used to login as a non-anonymous user. - '-v <name>': Set the service name for Apple's Bonjour. Only available on MacOS X when Bonjour support is compiled in. - '-w': Support the FXP protocol only for authenticated users. FXP works with IPv4 and IPv6 addresses. - '-W': Support the FXP protocol. FXP allows transfers between two remote servers without any file data going to the client asking for the transfer. However: **************************************************************************** *FXP IS AN INSECURE PROTOCOL* (third-party hosts can steal the current connection) . In Pure-FTPd, specific precautions have been taken to reduce FXP insertion attacks. But if your FTP server serves private data: NEVER ALLOW FXP ACCESS TO UNTRUSTED HOSTS. YOU CAN PLAY WITH IT ON AN INTERNAL SERVER, BUT _DON'T_ GIVE FXP ACCESS TO ANONYMOUS INTERNET USERS. **************************************************************************** It's why FXP is disabled by default on Pure-FTPd unless you explicitly enable it with '-W' or '-w'. - '-x': In normal operation mode, authenticated users can read/write files beginning with a dot ('.') . Anonymous users can't, for security reasons (like changing banners or a forgotten .rhosts) . When '-x' is used, authenticated users can download dot-files, but not overwrite/create them, even if they own them. That way, you can prevent hosted users from messing .qmail files. If you want to give user access to a special dot-file, create a symbolic link to the dot-file with a file name that has no dot in it and the client will be able to retrieve the file through that link. - '-X': This flag is identical to the previous one (writing dot-files is prohibited), but in addition, users can't even *read* files and directories beginning with a dot (like "cd .ssh") . **************************************************************************** When used in conjunction with "-a", members of the trusted group can bypass '-x'/'-X' restrictions. **************************************************************************** - '-y <max user logins>:<max anonymous logins>': This option only works if the server has been compiled with --with-peruserlimits. It restricts the number of concurrent sessions the same user can have. A null value ('0') means 'unlimited'. Here's a concrete example: /usr/local/sbin/pure-ftpd -y 3:20 -c 15 -C 5 -B Here, we allow: * A max total of 15 sessions. * 5 connections max coming from the same IP address. * 3 connections max with the same user name. * 20 anonymous users max. With such a setup, a single user can't easily fill all slots. - '-Y 0': Disable the TLS encryption layer (default). '-Y 1': Accept both standard and encrypted sessions. '-Y 2': Refuse connections that aren't using TLS security mechanisms, including anonymous sessions. The server must have been compiled with --with-tls and a valid certificate must be in place to get this feature. See the README.TLS file for more info about TLS. '-Y 3': Cleartext sessions are refused and only TLS compatible clients are accepted. Clear data connections are also refused, so private data connections are enforced. - '-z': Allow anonymous users to read files and directories starting with a dot ('.') . - '-Z': Try to protect customers against common mistakes to avoid your technical support being busy with stupid issues. Right now, the '-Z' switch prevents your users against making bad 'chmod' commands, that would deny access to files/directories to themselves. The switch may turn on other features in the future. If you are a hosting provider, turn this on. If you prefer long options (GNU-style) over standard ones, the following aliases are available. You can get this list at any time by typing 'pure-ftpd --help' . --(switches sorted by ##standard switches## lexical order)-- -0 --notruncate -1 --logpid <file> -4 --ipv4only -6 --ipv6only -8 --fscharset <charset> -9 --clientcharset <charset> -a --trustedgid <gid> -A --chrooteveryone -b --brokenclientscompatibility -B --daemonize -c --maxclientsnumber <number> -C --maxclientsperip <number> -d --verboselog -D --displaydotfiles -e --anonymousonly -E --noanonymous -f --syslogfacility <facility> -F --fortunesfile <file> -g --pidfile <path to pid file> -G --norename -h --help -H --dontresolve -i --anonymouscantupload -I --maxidletime <time (min)> -j --createhomedir -J --tlsciphersuite <ciphers> -k --maxdiskusagepct <percentage> -K --keepallfiles -l --login <auth> or <auth>:<config file> -L --limitrecursion <number:number> -m --maxload <load> -M --anonymouscancreatedirs -N --natmode -o --uploadscript -O --altlog <format>:<log file> -p --passiveportrange <minport:maxport> -P --forcepassiveip <ip address> -q --anonymousratio <upload ratio>:<download ratio> -Q --userratio <upload ratio>:<download ratio> -r --autorename -R --nochmod -s --antiwarez -S --bind <ip address,port> -t --anonymousbandwidth <bandwidth (KB/s)> -T --userbandwidth <bandwidth (KB/s)> or [<up bw>]:[<down bw>] -u --minuid <uid> -U --umask <mask> -v --bonjour <name> -V --trustedip <ip address> -w --allowuserfxp -W --allowanonymousfxp -x --prohibitdotfileswrite -X --prohibitdotfilesread -y --peruserlimits <per user max>:<max anonymous sessions> -Y --tls <0:no TLS | 1:TLS+cleartext | 2:enforce TLS | 3: enforce encrypted data channel as well> -z --allowdotfiles -Z --customerproof --(switches sorted by ##GNU-style long switches## lexical order)-- -W --allowanonymousfxp -z --allowdotfiles -w --allowuserfxp -O --altlog <format>:<log file> -t --anonymousbandwidth <bandwidth (KB/s)> -M --anonymouscancreatedirs -i --anonymouscantupload -e --anonymousonly -q --anonymousratio <upload ratio>:<download ratio> -s --antiwarez -r --autorename -S --bind <ip address,port> -b --brokenclientscompatibility -A --chrooteveryone -9 --clientcharset <charset> -j --createhomedir -Z --customerproof -B --daemonize -D --displaydotfiles -H --dontresolve -Y --tls <0:no TLS | 1:TLS+cleartext | 2:enforce TLS | 3:enforce encrypted data channel as well> -P --forcepassiveip <ip address> -F --fortunesfile <file> -8 --fscharset <charset> -h --help -4 --ipv4only -6 --ipv6only -K --keepallfiles -l --login <auth> or <auth>:<config file> -1 --logpid <file> -L --limitrecursion <number:number> -c --maxclientsnumber <number> -C --maxclientsperip <number> -k --maxdiskusagepct <percentage> -I --maxidletime <time (min)> -m --maxload <load> -u --minuid <uid> -N --natmode -E --noanonymous -R --nochmod -G --norename -0 --notruncate -v --bonjour <name> -p --passiveportrange <minport:maxport> -y --peruserlimits <per user max>:<max anonymous sessions> -g --pidfile <path to pid file> -X --prohibitdotfilesread -x --prohibitdotfileswrite -f --syslogfacility <facility> -J --tlsciphersuite <ciphers> -a --trustedgid <gid> -V --trustedip <ip address> -U --umask <mask> -o --uploadscript -T --userbandwidth <bandwidth (KB/s)> or [<up bw>]:[<down bw>] -Q --userratio <upload ratio>:<download ratio> -d --verboselog ------------------------ SETTING UP AN ANONYMOUS FTP ------------------------ If a 'ftp' user exists and its home directory exists, Pure-FTPd will accept anonymous login, as 'ftp' or 'anonymous'. The root directory of the files served when logged as 'anonymous' is the home directory of the 'ftp' user. There's no need for 'bin', 'lib', 'etc' and 'dev' directories, nor any external program. Don't chown the public files to 'ftp', just writable directories such as 'incoming'. ------------------------ DISPLAYING BANNERS ------------------------ If a '.banner' file is located in the 'ftp' user home directory (or in the root directory of a virtual server, see below), it will be printed when the client logs in. Put a nice ASCII-art logo with your name in that file. This file shouldn't be larger than 4000 bytes, or it won't be displayed. In each directory, you may also have a '.message' file. Its content will be printed when a client enters the directory. Such a file can contain important information ("Don't download version 1.7, it's broken!") . ------------------------ DISPLAYING A COOKIE ------------------------ A funny random message can be displayed in the initial login banner. The random cookies are extracted from a text file, in the standard "fortune" format. If you installed the "fortune" package, you should have a directory (usually /usr/share/fortune) with binary files (xxxx.dat) and text files (without the .dat extension) . To use Pure-FTPd cookies, just add the name of a text file to the '-F' option. For instance: /usr/local/sbin/pure-ftpd -F /usr/share/fortune/zippy If you want to have your own fortune files, just create a text file with the following structure. Hello... this is the first fortune... % Welcome to the real world. % Follow the white rabbit. % Have fun... Well... lotsa fun! % Yop is good for you. Goddit? Fortunes are delimited by a '%' sign on a single line. But a fortune itself can be multi-line (see the fourth example) . For security paranoia, the text file has to be readable by everybody (chmod 644 the file if necessary), or the server will ignore it. Of course, the fortune file can contain a single message. ------------------------ PER-USER CHROOT() RULES ------------------------ Apart from the "-a" flag, Pure-FTPd has another way to fine-tune chroot() rules. Let's take an /etc/passwd entry: mimi:x:501:100:Mimi:/home/mimi:/bin/zsh Without any special rule, mimi will be able to log in and to retrieve any public-readable file in the filesystem. Now, let's change a bit of its home directory: mimi:x:501:100:Mimi:/home/mimi/./:/bin/zsh So what? Mimi's home directory is still the same and common applications shouldn't notice any difference. But Pure-FTPd understands "chroot() until /./". So when mimi next carries out a FTP log in, only the /home/mimi directory will be reachable, not the whole filesystem. If you don't like the "-a" and its trusted gid thing, this is a good way to only chroot() some users. Another trick is to add something after "/./": mimi:x:501:100:Mimi:/home/mimi/./public_html:/bin/zsh When Mimi will log in, two things will happen: - chroot("/home/mimi") so that Mimi can't see anything but her home directory. - chdir("public_html") so the session will start in the public_html directory. "cd .." is still allowed, though. That "url-style" handling is especially handy for FTP-only users (ie. without shell access) . If a user is chrooted with the /./ trick *and* belongs to the trusted group (-a) he *will* be chrooted, but he will have no ratio and will be allowed to access dot files. ------------------------ RATIOS ------------------------ If you want to force people to upload new files before being able to download other files, ratios are for you. It's a very good way to get lotsa fresh stuff on a public FTP server and a must for warez traders. I don't like that kind of business, but well... Pure-FTPd has to be designed to please everybody. To enable ratios, just use the '-q' option, followed by the upload:download ratio: -q 2:5 ...means that an anonymous user has to upload at least 2 Mb of goodies to be able to download 5 Mb. If ratios should apply to everyone (anon and non-anon), use the '-Q' option the same way. Note: 'root' never has ratios. Neither have users of the trusted group when '-Q' in used with the '-a' or '-A' option. ------------------------ BANDWIDTH THROTTLING ------------------------ Pure-FTPd has an interesting built-in feature: simple bandwidth throttling. * You want to limit FTP throughput so that uploading and downloading files through that protocol can't fill up your network bandwidth. -> Compile Pure-FTPd with --with-throttling -> Run it with the '-T' flag, followed by a number. That number is the maximum bandwidth a user can use in a session, in kilobytes/seconds. * You want to allow less bandwidth to your anonymous users than your authenticated ones. So that during a bandwidth starvation, real users can still upload/download properly. -> Compile Pure-FTPd with --with-throttling -> Run it with the '-t' flag, followed by a number. Example: /usr/local/sbin/pure-ftpd -t 64 And uploading/downloading files can't take more than 64 KB/sec whatever real bandwidth you have. * It is possible to have different bandwidth limits for uploads and for downloads. '-t' and '-T' can indeed be followed by two numbers delimited by a column (':') . The first number is the upload bandwidth and the next one applies only to downloads. One of them can be left blank which means infinity. Example 1: 256 KB/s for uploads, 64 KB/s for downloads /usr/local/sbin/pure-ftpd -t 256:64 Example 2: 256 KB/s for uploads, no limit for downloads /usr/local/sbin/pure-ftpd -t 256: Example 3: no limit for uploads, 64 KB/s for downloads /usr/local/sbin/pure-ftpd -t:64 With no column, the value applies to both, so '-t 64' is an alias for '-t 64:64' . * When Pure-FTPd serves a session with restricted bandwidth, it decreases its process priority to 10. So, '-t 0' makes sense: during a CPU starvation, authenticated sessions may be more responsible than anonymous ones. '-T 0' is quite useless, but it also works and it will always be nice to the server process. * If you need advanced bandwidth management, have a look at your kernel Q.O.S. abilities. ------------------------ VIRTUAL SERVERS ------------------------ Using Virtual servers is a convenient way of hosting several FTP sites on the same computer. Let's say, you got two customers. The former owns the 'cgx.org' domain name, while the latter owns the 'example.com' domain name. Both are hosted on the same computer, but they don't want to share the same files. ftp://ftp.cgx.org/ should show different content than ftp://ftp.example.com/ . The FTP protocol doesn't allow name-based selection. So, if you want to host <N> different virtual FTP servers on the same host and keep the standard port, you need <N> different IP addresses. Yes, Sir. Or use HTTP. Assign the needed IP addresses to your network adapter (with "ifconfig eth0:x ..." or "ip addr add dev eth0 a.b.c.d"). Now, create a /etc/pure-ftpd directory if it doesn't exist: mkdir /etc/pure-ftpd To add a virtual FTP server, you only need to create a symbolic link in /etc/pure-ftpd/ from the virtual host IP to the directory that contains the file for that virtual host. Example: ln -s /home/customers/example.com/ftp /etc/pure-ftpd/216.226.17.77 ln -s /home/customers/cgx.org/ftp /etc/pure-ftpd/212.73.209.252 Done! Put the CGX files in /home/customers/cgx.org/ftp/ and the Example files in /home/customers/example.com/ftp/ . With that feature, every account on the server can have its own public anonymous FTP area. If you are providing hosting services, this is a nice feature for your customers. * WARNING *: it also means that your customers can create "incoming" directories with 1777 permissions. It can be nice, but it can also fill up your disk with warez. You can stop uploads for anonymous users with the '-i' (or --anonymouscantupload) option. By default, all IP addresses assigned to your server can be accessed by real or anonymous users. You can restrict this with -e (only anonymous) or -E (only real) . A more flexible way is to use '-V <ip address>' to define a "trusted" IP address. When a client connects to that trusted IP, anonymous and real logins are permitted. But on all other IP, only anonymous users are permitted. If you are a hosting service provider and if each customer has its own IP address, it may be a nice idea to have a trusted IP you give to all your customers, so that they can manage the files in their account. That IP is the same for all customers. You can easily restrict access to that IP with firewall rules if your customers have static IP addresses. Use '-V <trusted ip>' and link /etc/pure-ftpd/<customer ip> to ~customer/ftp . Every customer will have his own *anonymous only* FTP server and hackers will have to find the trusted IP to get in. ------------------------ IPv6 SUPPORT ------------------------ Pure-FTPd has full IPv6 support (native IPv6 addresses and 4-in-6 addresses). But use a super-server that also understands the IPv6 protocol, like Rlinetd or Xinetd. Recent versions of Inetd should also be ok (unverified). IPv6 is supported everywhere: logging, configuration switches, virtual hosts, protocol (EPSV/EPRT support), name resolution... --------------------- LOGGING --------------------- Log messages are sent to the syslog daemon. You can disable logging with '-f none'. If you want all FTP messages to be redirected to a file, say /var/log/ftp, add this line to your /etc/syslog.conf file: ftp.* /var/log/ftp Then restart your syslogd daemon: pkill -x -s HUP syslogd You can also drop your old "syslogd" and "klogd" programs for Metalog, an efficient alternative: http://metalog.sourceforge.net/ Names of uploaded/downloaded files are logged with paths like this: /home/ftp//pub/bla.jpg The double-slash ('//') is the chroot limit. --------------------- WATCHING CURRENT SESSIONS --------------------- Since 0.97.7, you can type 'pure-ftpwho' at any time to watch current active sessions. If typing 'pure-ftpwho' answers 'Command not found', you have to add /usr/local/sbin in your PATH environment variable. The default output looks like this: +------+---------+-------+------+-------------------------------------------+ | PID | Login |For/Spd| What | File/IP | +------+---------+-------+------+-------------------------------------------+ | 2239 | jedi | 00:17 | D/L | XFree86-clients-4.0.3.tar.gz | | '' | '' | 41K/s| 33% | -> nestea.funboard.de | +------+---------+-------+------+-------------------------------------------+ | 2385 | ftp | 00:02 | IDLE | | | '' | '' | | | -> gw2.crn.kjop.co.uk | +------+---------+-------+------+-------------------------------------------+ 'D/L' means that the client is downloading and 'U/L' means he's uploading some file whose name is shown in the next column. '33%' is the real-time completion of the current operation. '41K/s' is the bandwidth used by the client. You can track down who's starving your bandwidth with this. The 'pureftp-who' command accepts interesting options: '-c': the program is called via a web server (CGI interface) . Output is a full HTML page with the initial content-type header. This option is automatically enabled if an environment variable called GATEWAY_INTERFACE is found. This is the default if you can access the program from a CGI-enabled web server (Apache, Roxen, Caudium, WN, ...) . '-h': show command-line options summary. '-n': don't resolve host names and only show IP addresses (faster). '-s': output an easily parsable format for shell scripts (but not very user friendly) . There's only one line per client, with only numeric data, delimited by a '|' character. It's not very human-readable, but it's designed for easy parsing by shell scripts (cut/sed) . '|' characters in user names or file names are quoted ('|' becomes '\|') . Type 'pure-ftpwho -h' to check the format. '-w': output a complete HTML page (web mode). '-W': output an HTML page with no header and no footer. This is an embedded mode, suitable for inline calls from CGI, SSI or PHP scripts. '-x': output well-formed XML data for post-processing. This is the most accurate mode. Time is in seconds and file sizes are in bytes (in other output formats, sizes are in kbytes for easier readability) . '-v': verbose output in text mode. Additional info includes the size of files being downloaded/uploaded, the local IP or local host name and the connection port. This is especially useful for virtual hosts. Here's a sample output of 'pure-ftpwho -v': +------+---------+-------+------+-------------------------------------------+ | PID | Login |For/Spd| What | File/Remote IP/Size(Kb)/Local IP | +------+---------+-------+------+-------------------------------------------+ | 9086 | j | 00:04 | DL | linux-2.4.4.tar.bz2 | | '' | '' | 22K/s| 27% | -> localhost | | '' | '' | | | Total size: 20859 Transferred: 5632 | | '' | '' | | | <- localhost:21 | +------+---------+-------+------+-------------------------------------------+ ------------------------ AFTER AN UPLOAD ------------------------ After an upload, any external program or shell script can be spawned with the name of the newly uploaded file as an argument. You can use that feature to automatically send a mail when a new file arrives. Or you can pass it to a moderation system, an anti-virus, a digest generator or whatever you decide can be done with a file. To support this, the server has to be configured --with-uploadscript at compilation time. Upload scripts won't be spawned on unreadable directories. So it's highly recommended to use upload scripts with the --customerproof run-time option and without unreadable parent directories. To tell the FTP server to use upload scripts, it has to be launched with the '-o' option. Finally, you have to run another daemon called 'pure-uploadscript' provided by this package. IMPORTANT: YOU MUST START PURE-FTPD _FIRST_ and _THEN_ START PURE-UPLOADSCRIPT. THE REVERSE ORDER WON'T WORK. For security purposes, the server never launches any external program. It's why there is a separate daemon, that reads new uploads pushed into a named pipe by the server. Uploads are processed synchronously and sequentially. It's why on loaded or untrusted servers, it might be a bad idea to use pure-uploadscript with lengthy or cpu-intensive scripts. The easiest way to run pure-uploadscript is 'pure-uploadscript -r <script>': /usr/local/sbin/pure-uploadscript -r /bin/antivirus.sh The absolute path of the newly uploaded file is passed as a first argument. Some environment variables are also filled with interesting values: - UPLOAD_SIZE : the size of the file, in bytes. - UPLOAD_PERMS : the permissions, as an octal value. - UPLOAD_UID : the uid of the owner. - UPLOAD_GID : the group the file belongs to. - UPLOAD_USER : the name of the owner. - UPLOAD_GROUP : the group name the file belongs to. - UPLOAD_VUSER : the full user name, or the virtual user name. (127 chars max) There are also some options to "pure-uploadscript": - '-u <uid>' and '-g <gid>' to switch the account pure-uploadscript will run as. The script will be spawned with the same identity. - '-B' to fork in background. Please have a look at the man page ('man pure-uploadscript') for additional info. ------------------------ LISTING DIRECTORIES ------------------------ The built-in 'ls' supports all common options of a regular 'ls' command. Here are the ones you should know for a better life with FTP: - '-l': verbose listing, reporting dates, owners, perms and sizes. - '-a': also lists files and directories beginning with a dot. - '-F': adds a '/' after directory names. - '-d': list the directory itself, not its content. - '-R': recursive listing. - '-S': sort by size. - '-t': sort by date. - '-r': reverse the sorting order. If you aren't very familiar with Unix, log in to your FTP server and try these variants: ls ls -F ls -l ls -la ls -lR ls -Sl ls -Slr ls -tl ls -tlr Globbing is also supported. So if you are looking for a GNOME RPM in <I don't know the directory name>/gnome-xxxxxxxx.rpm , you can find it that way: ls */gnome*.rpm ------------------------ VIRTUAL QUOTAS ------------------------ With virtual quotas, you can restrict the maximum number of files and the total size of a user directory. These quotas are "virtual" because they aren't handled at kernel-level, but by the FTP server itself. There are some advantages over kernel quotas: - Virtual quotas are specific to the FTP server. You can have different system quotas to handle other files (eg. mail) on the same partition. - You can have different virtual quotas for every user, even if they share the same system uid. - Virtual quotas are working even on filesystems that don't support system quotas. However, virtual quotas are slower and can't be as reliable as kernel quotas, so don't trust them ultimately, they are probably races allowing to bypass them. Also the filesystem users directories are on must properly support file locking. Virtual quotas are implemented in Pure-FTPd as simple files called ".ftpquota", located in the home directory of chrooted users. This file only contains two numbers: the current number of files for this user and the total size of the directory (+ its subdirectories), in bytes. When a new file is uploaded, these numbers grow. When a file is deleted, these numbers get smaller. Simple. Of course, when virtual quotas are enabled for one user, that user must be 1) chrooted, 2) not allowed to write quota files, 3) not allowed to forbid access to some directories to fool the counter. Quotas can be enabled for all users for the -n (--quotas) option. This option is followed by the max number of files and the max size (in Megabytes) . Every user will have the same quota. Exception: members of the trusted group, if -a is enabled. You can also have different quotas for every user if you use PureDB or SQL databases. See the "README.Virtual-Users" file for more info about PureDB databases. So, if you want 1000 files max and 10 Mb max for all your customers, run the server like this: /usr/local/sbin/pure-ftpd -n 1000:10 ".ftpquota" files are created on demand when they are missing. However, when they are created, the server assumes that the account was empty. If this is not the case, you must run the "pure-quotacheck" utility to create an initial ".ftpquota" file. "pure-quotacheck" is a tool that computes the size and the number of files in a directory and create a ".ftpquota" file with this info. The syntax is: pure-quotacheck -u username/uid -d home directory [-g group/gid] For instance, if you want to summarize usage for the /home/ftpusers/john directory, whose files are owned by the "ftpusers" system account, just run: pure-quotacheck -u ftpusers -d /home/ftpusers/john You can run pure-quotacheck whenever you want, even when ".ftpquota" files are already there. This is even a good idea to run this for all users in crontab, so that stored quotas are always exact, even if something went wrong (server bug, filesystem corruption, savagely killed server, etc) . ------------------------ AUTHENTICATION ------------------------ Pure-FTPd supports multiple methods of authentication. To use a method, you must have it compiled in (check the ./configure options) . - To use Unix authentication (the traditional /etc/passwd file), add the following option when you run the server: -l unix - To use PAM authentication, add this: -l pam - To use PureDB (virtual users), add this: -l puredb:/path/to/puredb_database (read README.Virtual-Users for more info about PureDB indexed files) - To use LDAP directories, add this: -l ldap:/path/to/ldap_config_file (read README.LDAP for more info about LDAP directories) - To use MySQL databases, add this: -l mysql:/path/to/mysql_config_file (read README.MySQL for more info about MySQL databases) - To use Postgres databases, add this: -l pgsql:/path/to/postgres_config_file (read README.PGSQL for more info about Postgres databases) - To use external authentication handlers (with pure-authd), use: -l extauth:/path/to/authd/socket (read README.Authentication-Modules for more info about external authentication) Multiple authentication methods can be chained. For instance, you can run the server like this: /usr/local/sbin/pure-ftpd -lldap:/etc/pureftpd-ldap.conf \ -lpuredb:/etc/pureftpd.pdb -lunix Every method is tried in order. With the previous command line, an LDAP directory is probed first. If a user isn't found in the directory, a PureDB database is scanned for the same user name. If that user is still not found, /etc/passwd is scanned. If the user is found in the LDAP directory, but the given password is wrong, further authentication methods are skipped. If you don't specify any -l option, PAM is assumed by default if the server is compiled with PAM support and Unix is assumed by default otherwise. ------------------------ DIRECTORY ALIASES ------------------------ Directory aliases provides "shortcuts" for the "cd" command. For instance, if you define an alias called "pictures" for "/usr/misc/pictures", when an user will type "cd pictures" and if no real "pictures" directory exists, he will be automatically redirected to "/usr/misc/pictures". Unlike symbolic links, "cd pictures" will work from any directory. Tildes are *not* expanded. a user can get the list of available aliases with the following command: SITE ALIAS To support that feature, the server must be compiled with --with-diraliases passed to ./configure . To define alias/directory pairs, you must create a file called /etc/pureftpd-dir-aliases, whose format is: Alternating lines of alias and dir (this enables embedded whitespace in dir and alias without quoting rules) Optional blank lines Optional lines beginning with '#' as comments (no you can't put a '#' just anywhere) Example: pictures /usr/misc/pictures sources /usr/src # This is for the OpenBSD port tree pureftpd-port /usr/ports/net/pure-ftpd ------------------------ PRIVILEGE SEPARATION ------------------------ When privilege separation is enabled, each session will spawn two processes : a "privileged" process running as root, but that can only do very basic and trusted actions (binding a port and remove the ftpwho scoreboard) and the "client" process. The "client" process definitely revokes all privileges after authentication and chroot() and punctually communicates with the parent over a private channel. Privilege separation decreases performance of loaded servers, but it increases security and reliability. Enabling it is recommended. Some old broken operating systems may allow the ptrace() system call on processes that revoked privileges. On these platforms, enabling privilege separation is a bad idea if untrusted users also have shell access. Use the src/ptracetest program to check this. At least Solaris, ISOS, MirBSD, OpenBSD, DragonflyBSD, FreeBSD and Linux are known to be safe. ------------------------ CHARSETS (RFC2640) ------------------------ Since version 1.0.21, pure-ftpd has *experimental* support for charsets conversion. The server filesystem can use a different charset than the charset assumed by clients, and pure-ftpd translates file names through the iconv library. Some modern clients like lftp will also try to use UTF-8 if the server supports it. Thus, charsets conversion can be very useful when dealing with file names containing non-english characters. In order to support this, pure-ftpd has to be compiled with: ./configure ... --with-rfc2640 This is not supported by default because it requires libiconv. Then the server has to be started with --fscharset=<charset>. Replace <charset> with the charset of the server's filesystem. For instance: /usr/local/sbin/pure-ftpd --fscharset=ISO-8859-15 This is often enough to properly work with UTF-8 capable clients. But optionally, you can specify the default charset for clients, with --clientcharset: /usr/local/sbin/pure-ftpd --fscharset=iso-8859-15 --clientcharset=big5 ------------------------ OPTIMIZING FOR HIGH LOAD ------------------------ If you are going to use Pure-FTPd on a highly loaded server, here are some hints to get the best performances: - Compile with: env CFLAGS="-O2 -fomit-frame-pointer -fgcse -Os" ./configure --with-minimal --without-inetd --without-pam make install-strip - Run it in standalone mode. Don't use -C, don't enable pure-ftpwho nor pure-uploadscript (-o), nor per-user limits (-y) . - Increase your system max descriptors number and local port range. On a Linux kernel, you can try: echo 2000 > /proc/sys/fs/super-max echo 60000 > /proc/sys/fs/file-max ulimit -n 60000 echo 30000 65534 > /proc/sys/net/ipv4/ip_local_port_range - On a Linux kernel, disable syncookies, ecn, timestamps and window scaling: echo 0 > /proc/sys/net/ipv4/tcp_syncookies echo 0 > /proc/sys/net/ipv4/tcp_ecn echo 0 > /proc/sys/net/ipv4/tcp_timestamps echo 0 > /proc/sys/net/ipv4/tcp_window_scaling - Disable access time update on your mounted filesystems. On a Linux system, just add 'noatime,nodiratime' for each mount point in your /etc/fstab file. - Disable syslog output and DNS lookups. Run it with: /usr/local/sbin/pure-ftpd -f none -H For FreeBSD, DJ_Oggy recommends the following setting: >>> QUOTE: Drop into single user mode (do a shutdown now or boot -s) and enter tunefs -n enable <filesystem> i sugest / /usr /var In /etc/fstab add ",noatime" to the options of all filesystems. In /boot/loader.conf add the following: hw.ata.wc="1" kern.ipc.nmbclusters="60000" In /etc/sysctl.conf add the following: vfs.vmiodirenable=1 kern.ipc.maxsockbuf=2097152 kern.ipc.somaxconn=8192 kern.ipc.maxsockets=16424 kern.maxfiles=65536 kern.maxfilesperproc=32768 net.inet.tcp.rfc1323=1 net.inet.tcp.delayed_ack=0 net.inet.tcp.sendspace=65535 net.inet.tcp.recvspace=65535 net.inet.udp.recvspace=65535 net.inet.udp.maxdgram=57344 net.local.stream.recvspace=65535 net.local.stream.sendspace=65535 give it two asprin, a reboot and call me in the morning!!!!! <<< END OF QUOTE ------------------------ KNOWN ISSUES ------------------------ - On non-linux systems, '-c' only works in standalone mode. - You should always avoid the use of spaces in login names: applications that are parsing log files often choke on this. - Incomplete transfers aren't logged in alternative formats. - On Solaris, to get chroot to work with pure-ftpd you need a dev directory in your new rootdir with these: crw-rw-rw- 1 root other 11, 42 Dec 10 15:02 tcp crw-rw-rw- 1 root other 105, 1 Dec 10 15:02 ticotsord crw-rw-rw- 1 root other 11, 41 Dec 10 15:03 udp crw-rw-rw- 1 root other 13, 12 Dec 10 15:03 zero else you get this ftp> ls 425 Can't create the data socket: Bad file number. If all your users are chrooted, you have to create these files in every home directory. Here's how: mkdir dev mknod dev/tcp c 11 42 chmod 0666 dev/tcp mknod dev/udp c 11 41 mknod dev/zero c 13 12 mknod dev/ticotsord c 105 1 (Reported by Kenneth Stailey) - Resuming ASCII transfers is refused. ASCII transfers are hell, because they are consuming CPU time both at client and server sides. And they even consume *more* bandwidth than binary transfers. But they allow Windows clients to upload scripts to Unix servers, stripping these nasty ^M signs. ASCII transfers are implemented in Pure-FTPd. But they can't be resumed and this is intentional. To restart an ASCII transfer, the file has to be read and analyzed byte by byte. It can be very long and by sending two trivial commands, a client can completely kill a server (take a lot of CPU and disk resources) . And there's no workaround. Another point is that while RFC describe a way to resume ASCII transfers, many clients and servers implement them in another way. The result is that resumed ASCII transfers can lead to data corruption. Some major servers didn't follow RFC, so some clients did the same mistake to support these servers, while some other modern clients and servers are trying to fully conform to RFC. So when clients and servers are speaking the same dialect, it works. When it's not the case, you get corrupted files. Messy, eh? And what if a customer uploads a script to your server and thinks he can safely delete it from its hard disk? If the remote file is corrupted, he will get really angry. It's why Pure-FTPd *refuses* to resume ASCII transfers. If a customer tells you that he isn't able to upload/download a partially transferred ASCII file, please tell them to remove the partial file and to retransfer it again. This is a safe bet. ------------------------ DOWNLOADING PURE-FTPD ------------------------ Pure-FTPd home page is: https://www.pureftpd.org/ . Git repository: https://github.com/jedisct1/pure-ftpd Thank you, -Frank DENIS "Jedi/Sector One" <j at pureftpd dot org>
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