ftpd.tproj/ftpd.8

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  32 .\"     @(#)ftpd.8      8.3 (Berkeley) 6/1/94
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  34 .Dd June 1, 1994
  35 .Dt FTPD 8
  36 .Os BSD 4.2
  37 .Sh NAME
  38 .Nm ftpd
  39 .Nd
  40 Internet File Transfer Protocol server
  41 .Sh SYNOPSIS
  42 .Nm ftpd
  43 .Op Fl dl
  44 .Op Fl T Ar maxtimeout
  45 .Op Fl t Ar timeout
  46 .Sh DESCRIPTION
  47 .Nm Ftpd
  48 is the
  49 Internet File Transfer Protocol
  50 server process.  The server uses the
  51 .Tn TCP
  52 protocol
  53 and listens at the port specified in the
  54 .Dq ftp
  55 service specification; see
  56 .Xr services 5 .
  57 .Pp
  58 Available options:
  59 .Bl -tag -width Ds
  60 .It Fl d
  61 Debugging information is written to the syslog using LOG_FTP.
  62 .It Fl l
  63 Each successful and failed
  64 .Xr ftp 1
  65 session is logged using syslog with a facility of LOG_FTP.
  66 If this option is specified twice, the retrieve (get), store (put), append,
  67 delete, make directory, remove directory and rename operations and
  68 their filename arguments are also logged.
  69 .It Fl T
  70 A client may also request a different timeout period;
  71 the maximum period allowed may be set to
  72 .Ar timeout
  73 seconds with the
  74 .Fl T
  75 option.
  76 The default limit is 2 hours.
  77 .It Fl t
  78 The inactivity timeout period is set to
  79 .Ar timeout
  80 seconds (the default is 15 minutes).
  81 .El
  82 .Pp
  83 The file
  84 .Pa /etc/nologin
  85 can be used to disable ftp access.
  86 If the file exists,
  87 .Nm
  88 displays it and exits.
  89 If the file
  90 .Pa /etc/ftpwelcome
  91 exists,
  92 .Nm
  93 prints it before issuing the
  94 .Dq ready
  95 message.
  96 If the file
  97 .Pa /etc/motd
  98 exists,
  99 .Nm
 100 prints it after a successful login.
 101 .Pp
 102 The ftp server currently supports the following ftp requests.
 103 The case of the requests is ignored.
 104 .Bl -column "Request" -offset indent
 105 .It Request Ta "Description"
 106 .It ABOR Ta "abort previous command"
 107 .It ACCT Ta "specify account (ignored)"
 108 .It ALLO Ta "allocate storage (vacuously)"
 109 .It APPE Ta "append to a file"
 110 .It CDUP Ta "change to parent of current working directory"
 111 .It CWD Ta "change working directory"
 112 .It DELE Ta "delete a file"
 113 .It HELP Ta "give help information"
 114 .It LIST Ta "give list files in a directory" Pq Dq Li "ls -lgA"
 115 .It MKD Ta "make a directory"
 116 .It MDTM Ta "show last modification time of file"
 117 .It MODE Ta "specify data transfer" Em mode
 118 .It NLST Ta "give name list of files in directory"
 119 .It NOOP Ta "do nothing"
 120 .It PASS Ta "specify password"
 121 .It PASV Ta "prepare for server-to-server transfer"
 122 .It PORT Ta "specify data connection port"
 123 .It PWD Ta "print the current working directory"
 124 .It QUIT Ta "terminate session"
 125 .It REST Ta "restart incomplete transfer"
 126 .It RETR Ta "retrieve a file"
 127 .It RMD Ta "remove a directory"
 128 .It RNFR Ta "specify rename-from file name"
 129 .It RNTO Ta "specify rename-to file name"
 130 .It SITE Ta "non-standard commands (see next section)"
 131 .It SIZE Ta "return size of file"
 132 .It STAT Ta "return status of server"
 133 .It STOR Ta "store a file"
 134 .It STOU Ta "store a file with a unique name"
 135 .It STRU Ta "specify data transfer" Em structure
 136 .It SYST Ta "show operating system type of server system"
 137 .It TYPE Ta "specify data transfer" Em type
 138 .It USER Ta "specify user name"
 139 .It XCUP Ta "change to parent of current working directory (deprecated)"
 140 .It XCWD Ta "change working directory (deprecated)"
 141 .It XMKD Ta "make a directory (deprecated)"
 142 .It XPWD Ta "print the current working directory (deprecated)"
 143 .It XRMD Ta "remove a directory (deprecated)"
 144 .El
 145 .Pp
 146 The following non-standard or
 147 .Tn UNIX
 148 specific commands are supported
 149 by the
 150 SITE request.
 151 .Pp
 152 .Bl -column Request -offset indent
 153 .It Sy Request Ta Sy Description
 154 .It UMASK Ta change umask, e.g. ``SITE UMASK 002''
 155 .It IDLE Ta set idle-timer, e.g. ``SITE IDLE 60''
 156 .It CHMOD Ta change mode of a file, e.g. ``SITE CHMOD 755 filename''
 157 .It HELP Ta give help information.
 158 .El
 159 .Pp
 160 The remaining ftp requests specified in Internet RFC 959
 161 are
 162 recognized, but not implemented.
 163 MDTM and SIZE are not specified in RFC 959, but will appear in the
 164 next updated FTP RFC.
 165 .Pp
 166 The ftp server will abort an active file transfer only when the
 167 ABOR
 168 command is preceded by a Telnet "Interrupt Process" (IP)
 169 signal and a Telnet "Synch" signal in the command Telnet stream,
 170 as described in Internet RFC 959.
 171 If a
 172 STAT
 173 command is received during a data transfer, preceded by a Telnet IP
 174 and Synch, transfer status will be returned.
 175 .Pp
 176 .Nm Ftpd
 177 interprets file names according to the
 178 .Dq globbing
 179 conventions used by
 180 .Xr csh 1 .
 181 This allows users to utilize the metacharacters
 182 .Dq Li \&*?[]{}~ .
 183 .Pp
 184 .Nm Ftpd
 185 authenticates users according to three rules.
 186 .Pp
 187 .Bl -enum -offset indent
 188 .It
 189 The login name must be in the password data base,
 190 .Pa /etc/passwd ,
 191 and not have a null password.
 192 In this case a password must be provided by the client before any
 193 file operations may be performed.
 194 .It
 195 The login name must not appear in the file
 196 .Pa /etc/ftpusers .
 197 .It
 198 The user must have a standard shell returned by
 199 .Xr getusershell 3 .
 200 .It
 201 If the user name is
 202 .Dq anonymous
 203 or
 204 .Dq ftp ,
 205 an
 206 anonymous ftp account must be present in the password
 207 file (user
 208 .Dq ftp ) .
 209 In this case the user is allowed
 210 to log in by specifying any password (by convention an email address for
 211 the user should be used as the password).
 212 .El
 213 .Pp
 214 In the last case,
 215 .Nm ftpd
 216 takes special measures to restrict the client's access privileges.
 217 The server performs a
 218 .Xr chroot 2
 219 to the home directory of the
 220 .Dq ftp
 221 user.
 222 In order that system security is not breached, it is recommended
 223 that the
 224 .Dq ftp
 225 subtree be constructed with care, following these rules:
 226 .Bl -tag -width "~ftp/pub" -offset indent
 227 .It Pa ~ftp
 228 Make the home directory owned by
 229 .Dq root
 230 and unwritable by anyone.
 231 .ne 1i
 232 .It Pa ~ftp/bin
 233 Make this directory owned by
 234 .Dq root
 235 and unwritable by anyone (mode 555).
 236 The program
 237 .Xr ls 1
 238 must be present to support the list command.
 239 This program should be mode 111.
 240 .It Pa ~ftp/etc
 241 Make this directory owned by
 242 .Dq root
 243 and unwritable by anyone (mode 555).
 244 The files
 245 .Xr passwd 5
 246 and
 247 .Xr group 5
 248 must be present for the
 249 .Xr ls
 250 command to be able to produce owner names rather than numbers.
 251 The password field in
 252 .Xr passwd
 253 is not used, and should not contain real passwords.
 254 The file
 255 .Pa motd ,
 256 if present, will be printed after a successful login.
 257 These files should be mode 444.
 258 .It Pa ~ftp/pub
 259 Make this directory mode 777 and owned by
 260 .Dq ftp .
 261 Guests
 262 can then place files which are to be accessible via the anonymous
 263 account in this directory.
 264 .El
 265 .Sh FILES
 266 .Bl -tag -width /etc/ftpwelcome -compact
 267 .It Pa /etc/ftpusers
 268 List of unwelcome/restricted users.
 269 .It Pa /etc/ftpwelcome
 270 Welcome notice.
 271 .It Pa /etc/motd
 272 Welcome notice after login.
 273 .It Pa /etc/nologin
 274 Displayed and access refused.
 275 .El
 276 .Sh SEE ALSO
 277 .Xr ftp 1 ,
 278 .Xr getusershell 3 ,
 279 .Xr syslogd 8
 280 .Sh BUGS
 281 The server must run as the super-user
 282 to create sockets with privileged port numbers.  It maintains
 283 an effective user id of the logged in user, reverting to
 284 the super-user only when binding addresses to sockets.  The
 285 possible security holes have been extensively
 286 scrutinized, but are possibly incomplete.
 287 .Sh HISTORY
 288 The
 289 .Nm
 290 command appeared in
 291 .Bx 4.2 .