.:. PURE-FTPD .:. Documentation for version 1.0.20 PDF version available from http://www.pureftpd.org/readme.pdf ------------------------ 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, NetBSD, OpenBSD, ISOS, EkkoBSD, MirBSD, BSDi, Solaris, Darwin, Tru64, Irix, AIX and HPUX. 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, SSL/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. A list of some companies successfully using it is available at http://www.pureftpd.org/users.shtml Pure-FTPd was also part of a crack-a-machine challenge with other software, and that machine never got compromised. 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 altough some portability work has been done in order to ease its port to other operating systems, only Linux FreeBSD, NetBSD, OpenBSD, ISOS, EkkoBSD, MirBSD, BSDi, 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. An unofficial Windows port is available from http://www.pureftpd.org/windows/ 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 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 1: On Linux systems, you will notice that the server is always running as root. This is intentional and more secure that servers who are changing their effective uid (and only effective uid, they still have root privileges in fact, use ps -U to see what servers are really running as root) . We are using Linux kernel-specific tricks to drop privileges that "ps" can't show. Note 2: To compile under Irix, you have to issue this before typing ./configure: export CC=cc export CFLAGS=-I/usr/freeware/include export LDFLAGS=-L/usr/freeware/lib32 To compile under Solaris 8, use GNU Make, not Solaris basic make. Then do: export PATH=/usr/ccs/bin:$PATH export MAKE=gmake Nota 3: 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 analys 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-certfile=: the file with the SSL certificate (see README.TLS). The default is /etc/ssl/private/pure-ftpd.pem . --with-cookie: display a fortune or a customized banner when an 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 and rendezvous. --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=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 . --with-largefile: support downloading of files larger than 2 gigabytes on 32-bit architectures. Transfering so huge files through FTP is a strange idea. And your filesystem has to support it. Your kernel and your libc as well. And of course, the FTP client has to be safe against large files, too. And when this feature is enabled, downloads can be a bit slower (or more cpu-intensive) than without it, due to a limitation of actual Linux kernels. To summarize: don't enable this for fun, just if you are really planning to download files over 2 gigabytes. --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= 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= 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) . --with-pam: use pluggable authentification 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= syntax. See the README.PGSQL file for more info about Postgres and Pure-FTPd. --with-probe-random-dev: Pure-FTPd uses /dev/arandom, /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 an 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) . Only enable this if you really plan to use system 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 an 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 "professionnal-looking" messages. --with-privsep: enable privilege separation (see notes about this later). --withrendez-vous: enable Rendezvous support on MacOS X (see the -v switch). /----------------------- "--without-" switches -----------------------/ --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-banner: don't display the initial banner. This is stupid security through obscurity. --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 like g2s, 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, like "--prefix=" to change the installation prefix, that defaults to "/usr/local/". 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 ------------------------ 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.rtchat.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 his 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.rtchat.com,21 -c 50 & And only 50 simultanous 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. ------------------------ SUPER-SERVER INSTALLATION ------------------------ Pure-FTPd can also run with the help of a super-server, like telnet, wu-ftp, finger or Qmail. 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: killall -HUP inetd If 'killall' 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: killall -USR2 xinetd **** Usage with TCPserver **** TCPServer is part of the ucspi-tcp package by Dan Bernstein. It's less bloated than inetd, less D.O.S.-prone and has interesting filtering abilities. 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') . **** Usage with G2S **** Add the following lines to your /etc/jnetd.cf file (or whatever configuration file you choose for G2S): { SERVICE ftp DESCRIPTION "Pure-FTPd" RUN /usr/local/sbin/pure-ftpd } Restart the 'jnetd' daemon and you're done. ------------------------ 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 recognised 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 immediatly switch to the new one as soon as the full file will have been transfered. This option is incompatible with virtual quotas. - '-1': log the PID of each session in syslog output. - '-4': only listen to IPv4 connections. - '-6': don't listen to IPv4, only listen to IPv6. - '-a ': 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 will have unrestricted access to the whole filesystem. So add a "staff", "admin" or "ftpadmin" group and put your trusted users in. 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. - '-b': Ignore parts of RFC standards in order to deal with some totally broken FTP clients, or broken firewalls/NAT boxes. - '-B': Have the standalone server start in background (daemonization). - '-c ': 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 ': Limit the number of simultanous 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 ': 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 ': Display a fortune cookie on login. The sentence is a random extract from the text 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 ': 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 ': 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. - '-k ': Don't allow uploads if the partition is more than % 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 ' or '-l :': Adds a new rule to the authentication chain. Please read the "Authentication" section, later in this README file. It's an important section. - '-L :': To avoid stupid denial-of-service attacks (or just CPU hogs), Pure-FTPd never displays more than 2000 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 ': Don't allow anonymous download if the load is above . A very efficient way to prevent overloading your server. Upload is still allowed, though. - '-M': Allow anonymous users to create directories. - '-n :': If the server has been compiled with support for virtual quotas, enforce these quota settings for all users (except members of the 'trusted' group) . 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'. - '-O :': 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: is a GMT timestamp (time()) and identifies the current session. 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 :': Use only ports in the range to 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 ': Force the specified IP address in reply to a PASV/EPSV/SPSV 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 :': Enable ratios for anonymous users. - '-Q :': 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 whoose 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 [,|,] [|]'. 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 ' and '-t ': Enable bandwidth limitation (see below) . is specified in kilobytes/seconds. To set up separate upload/download bandwidth, the []:[] syntax is supported. - '-u ': Don't allow uids below to log in. '-u 1' denies access to root (safe), '-u 100' denies access to virtual accounts on most Linux distros. - '-U :': 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 ': 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 ': Set the service name for Apple's Rendezvous. Only available on MacOS X when Rendezvous 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 explicitely 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 :': 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 SSL/TLS encryption layer (default). '-Y 1': Accept both standard and encrypted sessions. '-Y 2': Refuse connections that aren't using SSL/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 SSL/TLS. - '-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 -4 --ipv4only -6 --ipv6only -a --trustedgid -A --chrooteveryone -b --brokenclientscompatibility -B --daemonize -c --maxclientsnumber -C --maxclientsperip -d --verboselog -D --displaydotfiles -e --anonymousonly -E --noanonymous -f --syslogfacility -F --fortunesfile -g --pidfile -G --norename -h --help -H --dontresolve -i --anonymouscantupload -I --maxidletime