FTPD(8) - Linux man page online | Administration and privileged commands

Internet File Transfer Protocol server.

June 1, 1994
FTPD(8) BSD System Manager's Manual FTPD(8)


ftpd — Internet File Transfer Protocol server


ftpd [-dlADq] [-T maxtimeout] [-t timeout] [-a login-name]


Ftpd is the Internet File Transfer Protocol server process. The server uses the TCP proto‐ col and listens at the port specified in the “ftp” service specification; see services(5). Available options: -d Debugging information is written to the syslog using LOG_FTP. -l Each successful and failed ftp(1) session is logged using syslog with a facility of LOG_FTP. If this option is specified twice, the retrieve (get), store (put), append, delete, make directory, remove directory and rename operations and their filename arguments are also logged. -A Only anonymous login is allowed. -D ftpd enters daemon-mode. That allows ftpd to be run without inetd. -q Quiet mode. No information about the version of the ftpd is given to the client. -T A client may also request a different timeout period; the maximum period allowed may be set to timeout seconds with the -T option. The default limit is 2 hours. -t The inactivity timeout period is set to timeout seconds (the default is 15 minutes). -a Give anonymous another login-name (anonymous and ftpd will still work). The file /etc/nologin can be used to disable ftp access. If the file exists, ftpd displays it and exits. If the file /etc/ftpwelcome exists, ftpd prints it before issuing the “ready” message. If the file /etc/motd exists, ftpd prints it after a successful login. The ftp server currently supports the following ftp requests. The case of the requests is ignored. Request Description ABOR abort previous command ACCT specify account (ignored) ALLO allocate storage (vacuously) APPE append to a file CDUP change to parent of current working directory CWD change working directory DELE delete a file HELP give help information LIST give list files in a directory (“ls -lgA”) MKD make a directory MDTM show last modification time of file MODE specify data transfer mode NLST give name list of files in directory NOOP do nothing PASS specify password PASV prepare for server-to-server transfer PORT specify data connection port PWD print the current working directory QUIT terminate session REST restart incomplete transfer RETR retrieve a file RMD remove a directory RNFR specify rename-from file name RNTO specify rename-to file name SITE non-standard commands (see next section) SIZE return size of file STAT return status of server STOR store a file STOU store a file with a unique name STRU specify data transfer structure SYST show operating system type of server system TYPE specify data transfer type USER specify user name XCUP change to parent of current working directory (deprecated) XCWD change working directory (deprecated) XMKD make a directory (deprecated) XPWD print the current working directory (deprecated) XRMD remove a directory (deprecated) The following non-standard or UNIX specific commands are supported by the SITE request. Request Description UMASK change umask, e.g. ``SITE UMASK 002'' IDLE set idle-timer, e.g. ``SITE IDLE 60'' CHMOD change mode of a file, e.g. ``SITE CHMOD 755 filename'' HELP give help information. The remaining ftp requests specified in Internet RFC 959 are recognized, but not imple‐ mented. MDTM and SIZE are not specified in RFC 959, but will appear in the next updated FTP RFC. The ftp server will abort an active file transfer only when the ABOR command is preceded by a Telnet "Interrupt Process" (IP) signal and a Telnet "Synch" signal in the command Telnet stream, as described in Internet RFC 959. If a STAT command is received during a data transfer, preceded by a Telnet IP and Synch, transfer status will be returned. Ftpd interprets file names according to the “globbing” conventions used by csh(1). This allows users to utilize the metacharacters “*?[]{}~”. Ftpd authenticates users according to three rules. 1. The login name must be in the password data base, /etc/passwd, and not have a null password. In this case a password must be provided by the client before any file operations may be performed. 2. The login name must not appear in the file /etc/ftpusers. 3. The user must have a standard shell returned by getusershell(3). 4. If the user name is “anonymous” or “ftp”, an anonymous ftp account must be present in the password file (user “ftp”). In this case the user is allowed to log in by specifying any password (by convention an email address for the user should be used as the password). In the last case, ftpd takes special measures to restrict the client's access privileges. The server performs a chroot(2) to the home directory of the “ftp” user. In order that sys‐ tem security is not breached, it is recommended that the “ftp” subtree be constructed with care, following these rules: ~ftp Make the home directory owned by “root” and unwritable by anyone. ~ftp/bin Make this directory owned by “root” and unwritable by anyone (mode 555). The program ls(1) must be present to support the list command. This program should be mode 111. ~ftp/etc Make this directory owned by “root” and unwritable by anyone (mode 555). The files passwd(5) and group(5) must be present for the ls command to be able to produce owner names rather than numbers. The password field in passwd is not used, and should not contain real passwords. The file motd, if present, will be printed after a successful login. These files should be mode 444. ~ftp/pub Make this directory mode 777 and owned by “ftp”. Guests can then place files which are to be accessible via the anonymous account in this direc‐ tory.


/etc/ftpusers List of unwelcome/restricted users. /etc/ftpwelcome Welcome notice. /etc/motd Welcome notice after login. /etc/nologin Displayed and access refused.


ftp(1), getusershell(3), syslogd(8)


The server must run as the super-user to create sockets with privileged port numbers. It maintains an effective user id of the logged in user, reverting to the super-user only when binding addresses to sockets. The possible security holes have been extensively scruti‐ nized, but are possibly incomplete.


The ftpd command appeared in 4.2BSD.
GNU inetutils June 1, 1994 GNU inetutils
This manual Reference Other manuals
ftpd(8) referred by ftp-ssl(1) | ftpchroot(5) | ftpd_selinux(8) | in.ftpd(8) | inetd(8) | inetutils-ftp(1) | inetutils-inetd(8) | inetutils-netrc(5) | lftp(1) | Net::FTP(3perl) | netkit-ftp(1) | netkit-netrc(5) | netrc-ssl(5) | opie(4freebsd) | pure-mrtginfo(8) | pyftpd(8) | qps(1) | securelevel(7freebsd) | security(7freebsd) | skey(4freebsd)
refer to chroot(2) | FTP(1) | getusershell(3) | group(5) | ls(1) | passwd(5) | services(5) | syslogd(8)
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