.\" SUCH DAMAGE.
.\"
.\" @(#)tftpd.8 8.1 (Berkeley) 6/4/93
+.\" $FreeBSD: src/libexec/tftpd/tftpd.8,v 1.15 2001/07/15 07:53:42 dd Exp $
.\"
-.Dd June 4, 1993
+.Dd September 14, 2000
.Dt TFTPD 8
-.Os BSD 4.2
+.Os
.Sh NAME
.Nm tftpd
-.Nd
-Internet Trivial File Transfer Protocol server
+.Nd Internet Trivial File Transfer Protocol server
.Sh SYNOPSIS
-.Nm tftpd
-.Op Fl l
-.Op Fl n
+.Nm /usr/libexec/tftpd
+.Op Fl cCln
+.Op Fl s Ar directory
+.Op Fl u Ar user
.Op Ar directory ...
.Sh DESCRIPTION
.Nm Tftpd
is a server which supports the
Internet Trivial File Transfer
-Protocol (\c
-.Tn RFC 783).
+Protocol
+.Pq Tn RFC 1350 .
The
.Tn TFTP
server operates
The use of
.Xr tftp 1
does not require an account or password on the remote system.
-Due to the lack of authentication information,
-.Nm tftpd
+Due to the lack of authentication information,
+.Nm
will allow only publicly readable files to be
accessed.
-Files containing the string ``/\|\fB.\|.\fP\|/'' are not allowed.
+Files containing the string ``/\|\fB.\|.\fP\|/'' or starting with
+``\|\fB.\|.\fP\|/'' are not allowed.
Files may be written only if they already exist and are publicly writable.
Note that this extends the concept of
.Dq public
The server should have the user ID with the lowest possible privilege.
.Pp
Access to files may be restricted by invoking
-.Nm tftpd
+.Nm
with a list of directories by including up to 20 pathnames
as server program arguments in
.Pa /etc/inetd.conf .
In this case access is restricted to files whose
names are prefixed by the one of the given directories.
-The given directories are also treated as a search path for
+The given directories are also treated as a search path for
relative filename requests.
.Pp
+The
+.Fl s
+option provides additional security by changing
+.Nm Ns No 's
+root directory, thereby prohibiting accesses outside of the specified
+.Ar directory .
+Because
+.Xr chroot 2
+requires super-user privileges,
+.Nm
+must be run as root.
+However, after performing the
+.Fn chroot ,
+.Nm
+will set its user id to that of the specified
+.Ar user ,
+or
+.Dq nobody
+if no
+.Fl u
+option is specified.
+.Pp
The options are:
.Bl -tag -width Ds
+.It Fl c
+Changes the default root directory of a connecting host via chroot based on the
+connecting IP address.
+This prevents multiple clients from writing to the same file at the same time.
+If the directory does not exist, the client connection is refused.
+The
+.Fl s
+option is required for
+.Fl c
+and the specified
+.Ar directory
+is used as a base.
+.It Fl C
+Operates the same as
+.Fl c
+except it falls back to
+.Fl s Ns No 's
+.Ar directory
+if a directory does not exist for the client's IP.
.It Fl l
-Logs all requests using
-.Xr syslog 3 .
+Log all requests using
+.Xr syslog 3
+with the facility of
+.Dv LOG_FTP .
+Note: Logging of
+.Dv LOG_FTP
+messages
+must also be enabled in the syslog configuration file,
+.Xr syslog.conf 5 .
.It Fl n
-Suppresses negative acknowledgement of requests for nonexistent
+Suppress negative acknowledgement of requests for nonexistent
relative filenames.
+.It Fl s Ar directory
+Cause
+.Nm
+to change its root directory to
+.Pa directory .
+After changing roots but before accepting commands,
+.Nm
+will switch credentials to an unprivileged user.
+.It Fl u Ar user
+Switch credentials to
+.Ar user
+(default
+.Dq nobody )
+when the
+.Fl s
+option is used.
+The user must be specified by name, not a numeric UID.
.El
.Sh SEE ALSO
.Xr tftp 1 ,
-.Xr inetd 8
+.Xr chroot 2 ,
+.Xr inetd 8 ,
+.Xr syslogd 8
+.Rs
+.%A K. R. Sollins
+.%T The TFTP Protocol (Revision 2)
+.%D July 1992
+.%O RFC 1350, STD 33
+.Re
.Sh HISTORY
The
.Nm
command appeared in
-.Bx 4.2 .
+.Bx 4.2 ;
+the
+.Fl s
+option was introduced in
+.Fx 2.2 ,
+the
+.Fl u
+option was introduced in
+.Fx 4.2 ,
+and the
+.Fl c
+option was introduced in
+.Fx 4.3 .
+.Sh BUGS
+Files larger than 33488896 octets (65535 blocks) cannot be transferred
+without client and server supporting blocksize negotiation (RFC1783).
+.Pp
+Many tftp clients will not transfer files over 16744448 octets (32767 blocks).
projects / apple / network_cmds.git / blobdiff