Provided by: netpipes_4.2-7_amd64 
NAME
netpipes - a package to manipulate BSD TCP/IP stream sockets
version 4.2
SYNOPSIS
faucet port (--in|--out|--err|--fd n)+ [--once] [--verbose] [--quiet] [--unix] [--foreignhost addr]
[--foreignport port] [--localhost addr] [--serial] [--daemon] [--shutdown (r|w) ] [--pidfile filename]
[--noreuseaddr] [--backlog n] [-[i][o][e][#3[,4[,5...]]][v][1][q][u][d][s]] [-p foreign-port] [-h
foreign-host] [-H local-host] command args
hose hostname port (--in|--out|--err|--fd n|--slave) [--verbose] [--unix] [--localport port] [--localhost
addr] [--retry n] [--delay n] [--shutdown [r|w][a] ] [--noreuseaddr] [-[i][o][e][#3[,4[,5...]]][s][v][u]]
[-p local-port] [-h local-host] command args
encapsulate --fd n [ --verbose ] [ --subproc [ --infd n[=sid] ] [ --outfd n[=sid] ] [ --duplex n[=sid] ]
[ --Duplex n[=sid] ] [ --DUPLEX n[=sid] ] [ --prefer-local ] [ --prefer-remote ] [ --local-only ] [
--remote-only ] ] [ --client ] [ --server ] -[#n][v][s[in][on][dn][ion][oin][l][r][L][R]] command args
...
sockdown [fd [how] ]
getpeername [ -verbose ] [ -sock ] [ fd ]
getsockname [ -verbose ] [ -peer ] [ fd ]
timelimit.netpipes [ -v ] [ -nokill ] time command args
DESCRIPTION
The netpipes package makes TCP/IP streams usable in shell scripts. It can also simplify client/server
code by allowing the programmer to skip all the tedious programming bits related to sockets and
concentrate on writing a filter/service.
``Why would anyone want to do that?''
-- Richard Stallman
faucet is the server end of a TCP/IP stream. It listens on a port of the local machine waiting for
connections. Every time it gets a connection it forks a process to perform a service for the connecting
client.
hose is the client end of a TCP/IP stream. It actively connects to a remote port and execs a process to
request a service.
encapsulate is an implementation of the Session Control Protocol. It allows you to multiplex several
streams across a single TCP session and also transmits remote exit status.
sockdown is a simple program designed to shut down part or all of the socket connection. It is primarily
useful when the processes connected to the socket perform both input and output.
getpeername and getsockname are two names for a program designed to print out the addresses of the ends
of a socket. getpeername prints the address of the remote end and getsockname prints the address of the
local end.
timelimit.netpipes limits the amount of foreground wallclock time a process may consume. After the time
limit runs out, it either kills the process, or exits and leaves it in the background.
EXAMPLES
Here is a simple command I often perform to transfer directory trees between machines. (rsh does not
work because one machine is connected using SLIP and .rhosts are out of the question).
server$ faucet 3000 --out tar cf - .
client$ hose server 3000 --in tar xvf -
Here is a minimal HTTP client. It is so minimal it speaks old HTTP.
cairo$ hose www.cis.ufl.edu 80 --in --out \
sh -c "(echo 'GET /'; sockdown) & cat > result"
And of course, there is Nick Trown's metaserver for Netrek
cairo$ hose metaserver.ecst.csuchico.edu 3521 --in cat
Allow me to apologize ahead of time for the convolutedness of the following example. It requires an
understanding of Bourne shell file descriptor redirection syntax (and illustrates why csh and tcsh suck
eggs). Do not try to type this from your tcsh command line. Get a bash (GNU's Bourne Again SHell).
Suppose you want to distinguish between stdout and stderr of a remote process
remote$ faucet 3000 --fd 3 \
encapsulate --fd 3 --infd 0 --outfd 1 --outfd 2 --subproc \
remote-app
local$ hose remote 3000 --fd 3 \
encapsulate --fd 3 --outfd 3 --infd 4 --infd 5 --subproc \
sh -c "cat 0<&4 3>&- & cat 0<&5 1>&2 3>&- & \
cat 1>&3 ; exec 3>&-"
Close all unneeded file descriptors when you spawn a background task. That's why the backgrounded cats
have 3>&-.
server$ faucet 3000 --in --out --verbose enscript -2rGhp -
client$ ps aux | hose server 3000 --in --out \
sh -c " (cat <&3; sockdown ) & cat >&4 " 3<&0 4>&1 | \
lpr -Pps422
#or perhaps this, but I haven't tested it
client$ ps aux | hose server 3000 --fd 3 \
sh -c " (cat >&3; sockdown 3 ) & cat <&3 " | \
lpr -Pps422
This proves that hose can be used as part of a pipeline to perform a sort of remote procedure call (RPC).
After you have figured out that example, you will know how to use Bourne shell to shuffle file
descriptors around. It is a handy skill.
Now we go to the extreme, but simplify things by using the --slave option of hose. The following is a
socket relay
gateway$ faucet 3000 -io hose server 4000 --slave
It's a handy little bugger when you want to tunnel through a firewall on an occasional basis. If you
experience ``hanging'' of the connection, try using the --netslave option instead of --slave. (telnet
proxies would benefit from this)
For those of you who use ssh, here's how to tunnel some information through an encrypted SSH port
forward.
server$ faucet 3000 -1v --fd 1 --foreignhost server echo blah
client$ ssh -n -x -L 3000:server:3000 server sleep 60 &
client$ hose localhost 3000 --fd 0 -retry 10 cat
The trick with ssh's port forwarding, is that the shutdown(2) system call causes ssh to close both halves
of the full-duplex connection instead of only one half. That's why you have to use --fd 1 and --fd 0.
If you need to be able to close half of the connection while still using the other, use the encapsulate
wrapper.
server$ faucet 3000 -1v --fd 3 --foreignhost server \
encapsulate --fd 3 --server -si0o1 tr a-z A-Z
client$ ssh -n -x -L 3000:server:3000 server sleep 60 &
client$ echo blah | hose localhost 3000 --fd 3 -retry 10 \
encapsulate --fd 3 --client
REMARK
The Debian package maintainer has renamed timelimit to the more expressive timelimit.netpipes, as there
exists a better alternative using the same short name, but which is actively maintained as an independent
software.
SEE ALSO
faucet(1), hose(1), encapsulate(1), sockdown(1), getpeername(1), timelimit.netpipes(1), timelimit(1).
BUGS
Report any bugs or feature requests to thoth@purplefrog.com
CREDITS
Thanks to Harbor Development Inc. for funding some of the netpipes development.
Thanks to Michal Jaegermann <michal@ellpspace.math.ualberta.ca> for some bug fixes and glibc portability
suggestions against 4.1.1 .
Big thanks to Joe Traister <traister@gate.net> for his signal handling patches, strerror surrogate, and
other assorted hacks.
COPYRIGHT
Copyright (C) 1995-98 Robert Forsman
This program is free software; you can redistribute it and/or modify it under the terms of the GNU
General Public License as published by the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even
the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public
License for more details.
You should have received a copy of the GNU General Public License along with this program; if not, write
to the Free Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
DOWNLOAD
Export Version: ftp://ftp.purplefrog.com/pub/netpipes/
U.S./Canada version with ssl-auth: http://www.cryptography.org/ , then find it in the network/
subdirectory.
AUTHOR
Robert Forsman
thoth@purplefrog.com
Purple Frog Software
http://web.purplefrog.com/~thoth/
October 28, 1997 NETPIPES(1)