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ftpd(8) System Manager's Manual ftpd(8) NAME ftpd - Describes File Transfer Protocol server daemon, including anony- mous service SYNOPSIS ftpd [-dl] [-ttimeout] [-Tmaxtimeout] FLAGS Debugging information is sent to the syslogd daemon (see syslogd(8)). Each FTP session, as well as additional information, such as the file name retrieved or stored, the number of bytes, and the attempted logins that failed, is sent to the syslogd daemon (see syslogd(8)). The inac- tivity time-out period will be set to time-out seconds. The maximum timeout period allowed may be set to timeout seconds with this option. SECURITY NOTE This security-sensitive command uses the SIA (Security Integration Ar- chitecture) routine as an interface to the security mechanisms. See ma- trix.conf(4) for more information. DESCRIPTION The ftpd command is the DARPA (Defense Advanced Research Projects Agency) Internet File Transfer Protocol server process. The server uses the TCP protocol and listens at the port specified in the FTP ser- vice specification; see services(4). The ftpd command includes two flags to control the information logged for the ftpd daemon. If the -d flag is specified, debugging informa- tion is logged. If the -l flag is specified, each ftp session, along with data for login failures and file operations, is logged. Refer to the syslogd(8) reference page for information on system log files. The FTP server will time out an inactive session after 15 minutes. If the -t flag is specified, the inactivity time-out period will be set to time-out seconds. A client may also request a different time-out pe- riod; the maximum period allowed may be set to time-out seconds with the -T flag. The default limit is 2 hours. The FTP server currently supports the following ftp requests; case is not distinguished: Description Abort previous command Specify account (ignored) Allocate storage (vacuously) Append to a file Change to par- ent of current working directory Change working directory Delete a file Give help information Give list files in a directory (ls -lgA) Make a directory Show last modification time of file Specify data transfer mode Give name list of files in directory Do nothing Specify password Prepare for server-to-server transfer Specify data connection port Print the current working directory Terminate session Restart incom- plete transfer Retrieve a file Remove a directory Specify rename-from file name Specify rename-to file name Nonstandard commands (see next section) Return size of file Return status of server Store a file Store a file with a unique name Specify data transfer structure Show operat- ing system type of server system Specify data transfer type Specify username Change to parent of current working directory (deprecated) Change working directory (deprecated) Make a directory (deprecated) Print the current working directory (deprecated) Remove a directory (deprecated) The following nonstandard or UNIX compatible commands are supported by the SITE request: Description Change umask (for example, SITE UMASK 002) Set idle timer (for example, SITE IDLE 60) Change mode of a file (for example, SITE CHMOD 755 filename) Give help information (for exam- ple, SITE HELP) The remaining ftp requests specified in Internet RFC959 are recognized, but not implemented. MDTM and SIZE are not specified in RFC959, 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 In- ternet RFC959. If a STAT command is received during a data transfer, preceded by a Telnet IP and Synch, transfer status will be returned. The ftpd command interprets file names according to the ``globbing'' conventions used by the C shell (see csh(1)). This interpretation al- lows users to utilize the metacharacters ``*?[]{}~''. The ftpd command authenticates users according to four rules: The user- name must be in the password database, /etc/passwd, and not have a null password. In this case, a password must be provided by the client be- fore any file operations may be performed. The username must not ap- pear in the /etc/ftpusers file. The user must have a standard shell returned by the getusershell() call (see getusershell(3)). If the username 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 this is given as the client host's name). The ftp command uses the default Type-of-Service values recommended by RFC1060, which are as follows: Low delay High throughput Anonymous FTP Configuration If you are creating an anonymous FTP account, ftpd takes special mea- sures to restrict the client's access privileges when the user logs in. The server executes a chroot call (see chroot(2)) to the home directory of the ftp user. In order that system security is not breached, it is recommended that you adhere to the following rules when creating direc- tories and files in the ftp subtree: Make the home directory owned by the superuser (root) and unwritable by anyone. Make this directory owned by the superuser and unwritable by anyone. The ls program (see ls(1)) must be present to support the list command. This program should have mode 111. Copy the ls program from /sbin/ls. This is the statically linked version of the ls command, which does not require shared library support. Be sure to copy the static version of ls from the /sbin directory, not the shared version from the /usr/bin direc- tory. Make this directory owned by the superuser and unwritable by anyone. The passwd and group files (see passwd(4) and group(4) ) must be present for the ls command to be able to pro- duce owner names rather than numbers. The password field in the passwd file is not used, and should not contain real encrypted passwords. These files should be mode 444. In this environment, the sia subdirectory (which you can copy from /etc/sia) must also be present for the ls command to be able to produce owner names rather than numbers. Make this di- rectory mode 777 and owned by ftp. Users should then place files that are to be accessible via the anonymous account in this directory. You can configure these values by specifying them in the /etc/iptos file. For more information, see iptos(4). FILES Specifies the command path. Contains the list of unauthorized users. CAUTIONS The anonymous account is inherently dangerous and should be avoided when possible. The server must run as the superuser to create sockets with privileged port numbers. It maintains an effective user ID of the logged in user, reverting to the superuser only when binding addresses to sockets. The possible security holes have been extensively scrutinized, but are pos- sibly incomplete. RELATED INFORMATION Commands: ftp(1), syslogd(8) Functions: getusershell(3) Files: iptos(4) delim off ftpd(8)