FTPD(8C) FTPD(8C) NAME ftpd - DARPA Internet File Transfer Protocol server SYNOPSIS /etc/ftpd [ -d ] [ -l ] [ -ttimeout ] DESCRIPTION _F_t_p_d is the DARPA Internet File Transfer Prototocol server process. The server uses the TCP protocol and listens at the port specified in the ‘‘ftp’’ service specification; see _s_e_r_v_i_c_e_s(5). If the -d option is specified, debugging information is written to the syslog. If the -l option is specified, each ftp session is logged in the sys‐ log. The ftp server will timeout an inactive session after 15 minutes. If the -t option is specified, the inactivity timeout period will be set to _t_i_m_e_o_u_t. The ftp server currently supports the following ftp requests; case is not distinguished. 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 -lg’’) MKD make a directory MODE specify data transfer _m_o_d_e NLST give name list of files in directory (‘‘ls’’) 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 RETR retrieve a file RMD remove a directory RNFR specify rename-from file name RNTO specify rename-to file name STOR store a file STOU store a file with a unique name STRU specify data transfer _s_t_r_u_c_t_u_r_e TYPE specify data transfer _t_y_p_e USER specify user name XCUP change to parent of current working directory XCWD change working directory XMKD make a directory XPWD print the current working directory XRMD remove a directory The remaining ftp requests specified in Internet RFC 959 are recog‐ nized, but not implemented. 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. _F_t_p_d interprets file names according to the ‘‘globbing’’ conventions used by _c_s_h(1). This allows users to utilize the metacharacters ‘‘*?[]{}~’’. _F_t_p_d authenticates users according to three rules. 1) The user name must be in the password data base, _/_e_t_c_/_p_a_s_s_w_d, and not have a null password. In this case a password must be provided by the client before any file operations may be per‐ formed. 2) The user name must not appear in the file _/_e_t_c_/_f_t_p_u_s_e_r_s. 3) The user must have a standard shell returned by _g_e_t_u_s_e_r_s_h_e_l_l(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 pass‐ word (by convention this is given as the client host’s name). In the last case, _f_t_p_d takes special measures to restrict the client’s access privileges. The server performs a _c_h_r_o_o_t(2) command to the home directory of the ‘‘ftp’’ user. In order that system security is not breached, it is recommended that the ‘‘ftp’’ subtree be constructed with care; the following rules are recommended. ~ftp) Make the home directory owned by ‘‘ftp’’ and unwritable by any‐ one. ~ftp/bin) Make this directory owned by the super-user and unwritable by anyone. The program _l_s(1) must be present to support the list commands. This program should have mode 111. ~ftp/etc) Make this directory owned by the super-user and unwritable by anyone. The files _p_a_s_s_w_d(5) and _g_r_o_u_p(5) must be present for the _l_s command to work properly. These files should be mode 444. ~ftp/pub) Make this directory mode 777 and owned by ‘‘ftp’’. Users should then place files which are to be accessible via the anonymous account in this directory. SEE ALSO ftp(1C), getusershell(3), syslogd(8) BUGS The anonymous account is inherently dangerous and should avoided when possible. 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 scrutinized, but are possibly incomplete. 4.2 Berkeley Distribution April 27, 1985 FTPD(8C)