NETPIPES(1)NETPIPES(1)NAMEnetpipes - 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 ...
ssl-auth --fd n ( --server | --client ) [ --cert file ] [ --key file ]
[ --verbose ] [ --verify n ] [ --CApath path/ ] [ --CAfile file ] [
--cipher cipher-list ] [ --criteria criteria-expr ] [ --subproc [
--infd n ] [ --outfd n ] ] [ -[#n][v][s[in][on]] ]
sockdown [fd [how] ]
getpeername [ -verbose ] [ -sock ] [ fd ]
getsockname [ -verbose ] [ -peer ] [ fd ]
timelimit [ -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 con‐
nection 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.
ssl-auth is an encryption filter that encapsulates stdin/stdout from a
subprocess (or its own stdin/stdout) in the Secure Socket Layer proto‐
col as implemented by the SSLeay library. It can be used to communi‐
cate with encrypted daemons (HTTPS daemons, or SSL IMAP daemons) and
can sometimes be used to jury-rig secure versions of such services.
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 limits the amount of foreground wallclock time a process can
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 fol‐
lowing 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 descrip‐
tors 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 connec‐
tion, try using the --netslave option instead of --slave. (telnet prox‐
ies 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
SEE ALSO
faucet (1), hose (1), encapsulate (1), sockdown (1), getpeername (1),
timelimit (1), ssl-auth (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 MER‐
CHANTABILITY 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)
