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ecatmur
Advocate
Joined: 20 Oct 2003
Posts: 3595
Location: Edinburgh
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 Posted: Tue Jan 06, 2004 1:43 am Post subject: [HOWTO] transparent lbxproxy X compression through ssh |
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lbxproxy can significantly increase the startup time of remote X applications (in my experience, by up to 50% on a 25ms latency connection). It runs on the client end and filters X traffic to the server - most X servers can decompress lbxproxy traffic.
The procedure to use lbxproxy via ssh is: | Code: | ssh me@client
DISPLAY=localhost:10.0 lbxproxy :63
export DISPLAY=:63 |
Obviously this gets a bit clumsy if you have to do this each time, so I have developed a way to automate it. On the remote client (the machine you ssh into) install lbxproxy and append to .ssh/rc:
| Code: | #!/bin/bash
if read proto cookie && [ -n "$DISPLAY" ]; then
if [ `echo $DISPLAY | cut -c1-10` = 'localhost:' ]; then
# X11UseLocalhost=yes
echo add unix:`echo $DISPLAY |
cut -c11-` $proto $cookie
else
# X11UseLocalhost=no
echo add $DISPLAY $proto $cookie
fi | /usr/X11R6/bin/xauth -q -
# Find a port to run lbxproxy on
for (( lbx_port=63; lbx_port < 1000; ++lbx_port )); do
/bin/fuser $((6000 + lbx_port))/tcp >/dev/null && continue
/usr/X11R6/bin/lbxproxy :$lbx_port -display $DISPLAY \
2>/dev/null &
break
done
unset lbx_port
fi |
Also append to .bashrc or whatever you use: | Code: | # lbxproxy magic - need command in ~/.ssh/rc or /etc/ssh/sshrc
if [ "$DISPLAY" ]; then
lbx_display=$(expr match \
"$(pgrep -l -U $UID -f "lbxproxy\>.* -display $DISPLAY\>")" \
'.* \(:[[:digit:]]\+\)\($\| \)')
if [ "$lbx_display" ]; then
export DISPLAY=$lbx_display
fi
unset lbx_display
fi
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The code in .ssh/rc is based on that in the sshd manpage.
You may need to correct paths if the remote machine is not a Gentoo box.
Hopefully you should see a speedup in remote X applications, for no incremental effort. |
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puddpunk
l33t
Joined: 20 Jul 2002
Posts: 681
Location: New Zealand
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| Posted: Tue Jan 06, 2004 2:25 am Post subject: |
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Thanks! Great tip, I'm making a note of this one as when I go back to work this is going to help a WHOLE lot.
Thanks Again,
Chris. |
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MasonMouse
Tux's lil' helper
Joined: 26 Nov 2002
Posts: 146
Location: Texas, USA
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| Posted: Thu Jan 08, 2004 9:01 pm Post subject: |
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| Just out of curiousity, how does this differ from or compare to using "ssh -XC" to forward and compress X connections? |
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ecatmur
Advocate
Joined: 20 Oct 2003
Posts: 3595
Location: Edinburgh
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| Posted: Fri Jan 09, 2004 9:28 pm Post subject: |
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| MasonMouse wrote: | | Just out of curiousity, how does this differ from or compare to using "ssh -XC" to forward and compress X connections? |
From the openssh (1) manpage:
-C Requests compression of all data (including stdin, stdout,
stderr, and data for forwarded X11 and TCP/IP connections). The
compression algorithm is the same used by gzip(1)
lbxproxy uses a compression algorithm specifically designed for X traffic, and also caches data to eliminate requests and mimimise round-trip traffic. |
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