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@relistan
Created March 22, 2012 16:36
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proxy ssh through a jump host without breaking all other ssh connections
Host *
ForwardAgent yes
ProxyCommand ~/bin/ssh-proxy.sh %h %p username@jump-host
ServerAliveInterval 10
ServerAliveCountMax 600
#!/bin/bash
# ------------------------------------------------------------------------------
# Use SOCKS proxy to proxy SSH through a jump host. This works in
# almost all circumstances and has the advantage of using only one
# SSH tunnel to the jump host for all concurrent ssh tunnels. It
# does not end the open connection to the jump host when the connection
# is closed.
# ------------------------------------------------------------------------------
# Author: Karl Matthias
# Date: Tue 31 Jan 2012
hostname=$1
port=$2
proxy_host=$3
usage() {
die "`basename $0`: [hostname] [port] [proxy_host]"
}
die() {
echo $1 >&2
exit 1
}
test -z $hostname && usage
test -z $port && usage
test -z $proxy_host && usage
nc -z -w 2 $hostname $port > /dev/null 2>&1
if [[ $? -eq 0 ]]; then
nc -w 300000 $hostname $port
else
nc -z -w 2 localhost 9090 > /dev/null 2>&1
if [[ $? -ne 0 ]]; then
ssh -f -N -D9090 $proxy_host
fi
nc -x localhost:9090 $hostname $port
fi
@relistan
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Tunneling Through a Jump Host

This will establish a SOCKS connection to your jump host. It will attempt to make a connection with netcat to the hostname you try to ssh to. If it's accessible directly, it will go directly. If it isn't it will automatically be proxied over the tunnel to the jump host. You will have to authenticate the tunnel the first time and then it will stay up in the background afterward. The ServerAliveInterval should help keep the tunnel up even through awful gateways like the Virgin SuperHub or over other firewalls with short timeouts.

If you have a reliable internal DNS zone available behind the jump host you can modify this to work on just those hosts by changing the Host line in the ssh config.

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