remote_cmds/tftpd.tproj/tftpd.8

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  30 .\"     from: @(#)tftpd.8       8.1 (Berkeley) 6/4/93
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  32 .Dd June 11, 2003
  33 .Dt TFTPD 8
  34 .Os
  35 .Sh NAME
  36 .Nm tftpd
  37 .Nd
  38 .Tn DARPA
  39 Internet Trivial File Transfer Protocol server
  40 .Sh SYNOPSIS
  41 .Nm
  42 .Op Fl d
  43 .Op Fl g Ar group
  44 .Op Fl i
  45 .Op Fl l
  46 .Op Fl n
  47 .Op Fl s Ar directory
  48 .Op Fl u Ar user
  49 .Op Ar directory ...
  50 .Sh DESCRIPTION
  51 .Nm
  52 is a server which supports the
  53 .Tn DARPA
  54 Trivial File Transfer Protocol.
  55 The
  56 .Tn TFTP
  57 server operates at the port indicated in the
  58 .Ql tftp
  59 service description; see
  60 .Xr services 5 .
  61 This server should not be started manually; instead, it should be run using
  62 .Xr launchd 8
  63 using the plist
  64 .Pa /System/Library/LaunchDaemons/tftp.plist .
  65 It may be started using the
  66 .Xr launchctl 1
  67 load command; refer to the documentation for that utility for more information.
  68 .Pp
  69 The use of
  70 .Xr tftp 1
  71 does not require an account or password on the remote system.
  72 Due to the lack of authentication information,
  73 .Nm
  74 will allow only publicly readable files to be accessed.
  75 Filenames beginning in ``\|\fB.\|.\fP\|/'' or
  76 containing ``/\|\fB.\|.\fP\|/'' are not allowed.
  77 Files may be written to only if they already exist and are publicly writable.
  78 .Pp
  79 Note that this extends the concept of
  80 .Qq public
  81 to include
  82 all users on all hosts that can be reached through the network;
  83 this may not be appropriate on all systems, and its implications
  84 should be considered before enabling tftp service.
  85 The server should have the user ID with the lowest possible privilege.
  86 .Pp
  87 Access to files may be restricted by invoking
  88 .Nm
  89 with a list of directories by including up to 20 pathnames
  90 as server program arguments in
  91 .Pa /System/Library/LaunchDaemons/tftp.plist .
  92 In this case access is restricted to files whose
  93 names are prefixed by the one of the given directories.
  94 The given directories are also treated as a search path for
  95 relative filename requests.
  96 .Pp
  97 The options are:
  98 .Bl -tag -width "directory"
  99 .It Fl d
 100 Enable verbose debugging messages to
 101 .Xr syslogd 8 .
 102 .It Fl g Ar group
 103 Change gid to that of
 104 .Ar group
 105 on startup.
 106 If this isn't specified, the gid is set to that of the
 107 .Ar user
 108 specified with
 109 .Fl u .
 110 .It Fl i
 111 Enable insecure mode, no
 112 .Xr realpath 3 .
 113 .It Fl l
 114 Logs all requests using
 115 .Xr syslog 3 .
 116 .It Fl n
 117 Suppresses negative acknowledgement of requests for nonexistent
 118 relative filenames.
 119 .It Fl s Ar directory
 120 .Nm
 121 will
 122 .Xr chroot 2
 123 to
 124 .Ar directory
 125 on startup.
 126 This is recommended for security reasons (so that files other than
 127 those in the
 128 .Pa /tftpboot
 129 directory aren't accessible).
 130 If the remote host passes the directory name as part of the
 131 file name to transfer, you may have to create a symbolic link
 132 from
 133 .Sq tftpboot
 134 to
 135 .Sq \&.
 136 under
 137 .Pa /tftpboot .
 138 .It Fl u Ar user
 139 Change uid to that of
 140 .Ar user
 141 on startup.
 142 If
 143 .Fl u
 144 isn't given,
 145 .Ar user
 146 defaults to
 147 .Dq nobody .
 148 If
 149 .Fl g
 150 isn't also given, change the gid to that of
 151 .Ar user
 152 as well.
 153 .El
 154 .Sh SEE ALSO
 155 .Xr tftp 1 ,
 156 .Xr launchd 8 ,
 157 .Xr launchctl 1 ,
 158 .Xr launchd.plist 5
 159 .Rs
 160 .%R RFC
 161 .%N 1350
 162 .%D July 1992
 163 .%T "The TFTP Protocol (Revision 2)"
 164 .Re
 165 .Rs
 166 .%R RFC
 167 .%N 2347
 168 .%D May 1998
 169 .%T "TFTP Option Extension"
 170 .Re
 171 .Rs
 172 .%R RFC
 173 .%N 2348
 174 .%D May 1998
 175 .%T "TFTP Blocksize Option"
 176 .Re
 177 .Rs
 178 .%R RFC
 179 .%N 2349
 180 .%D May 1998
 181 .%T "TFTP Timeout Interval and Transfer Size Options"
 182 .Re
 183 .Sh HISTORY
 184 The
 185 .Nm
 186 command appeared in
 187 .Bx 4.2 .
 188 .Pp
 189 The
 190 .Fl s
 191 flag appeared in
 192 .Nx 1.0 .
 193 .Pp
 194 The
 195 .Fl g
 196 and
 197 .Fl u
 198 flags appeared in
 199 .Nx 1.4 .
 200 .Pp
 201 IPv6 support was implemented by WIDE/KAME project in 1999.
 202 .Pp
 203 TFTP options were implemented by Wasabi Systems, Inc., in 2003,
 204 and first appeared in
 205 NetBSD 2.0 .
 206 .Sh BUGS
 207 Files larger than 33488896 octets (65535 blocks) cannot be transferred
 208 without client and server supporting blocksize negotiation (RFCs
 209 2347 and 2348).
 210 .Pp
 211 Many tftp clients will not transfer files over 16744448 octets (32767 blocks).
 212 .Sh SECURITY CONSIDERATIONS
 213 You are
 214 .Em strongly
 215 advised to set up
 216 .Nm
 217 using the
 218 .Fl s
 219 flag in conjunction with the name of the directory that
 220 contains the files that
 221 .Nm
 222 will serve to remote hosts (e.g.,
 223 .Pa /tftpboot ) .
 224 This ensures that only the files that should be served
 225 to remote hosts can be accessed by them.
 226 .Pp
 227 Because there is no user-login or validation within
 228 the
 229 .Tn TFTP
 230 protocol, the remote site will probably have some
 231 sort of file-access restrictions in place.
 232 The exact methods are specific to each site and therefore
 233 difficult to document here.