Here a basic script that you can use if you want to connect from your local box, via a middle linux machine, to a third host.
It will also allow you to use FoxyProxy on your browser and browse the internal network of the destination box.
BOX_A <==== MIDDLE_BOX ====> BOX_B
The goal is having access from BOX_A to BOX_B via MIDDLE_BOX
MIDDLE_BOX is the only one that can talk withBOX_A and BOX_B
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#!/bin/bash # # ==================================================== # # Tunnel from CURRENT_HOST to DEST_HOST via MIDDLE_BOX # # ==================================================== # # # The scripts connects the local port 8888 # to the SSH port on DEST_BOX via MIDDLE_BOX. # MIDDLE_BOX_HOST="bastion_server.localdomain.loc" MIDDLE_BOX_USER="username" MIDDLE_BOX_SSH_PORT="22" DEST_BOX_HOST="destination_host.domain.com" DEST_BOX_USER="username" DEST_BOX_SSH_PORT="22" LOC_PORT=8888 SOCK_PORT=9050 ############################################################ CHECK_TUNS=$(ps aux | grep "[s]sh -N -f -p $MIDDLE_BOX_SSH_PORT -L$LOC_PORT:$DEST_BOX_HOST:$DEST_BOX_SSH_PORT $MIDDLE_BOX_USER@$MIDDLE_BOX_HOST" | awk '{print $2}') N_TUNS=$(echo $CHECK_TUNS | wc -l) create_tunnel(){ # Create a connection between localhost:$LOC_PORT to MIDDLE_BOX:SSH_PORT # It will ask for MIDDLE_BOX's password # -N -f keep the connection open in background executing No commands ssh -N -f -p $MIDDLE_BOX_SSH_PORT -L$LOC_PORT:$DEST_BOX_HOST:$DEST_BOX_SSH_PORT $MIDDLE_BOX_USER@$MIDDLE_BOX_HOST echo "Created new tunnel" } check_tunnel(){ nc -w 1 -z localhost $LOC_PORT > /dev/null 2>&1 } reset_tunnel() { for PID in $CHECK_TUNS; do kill -9 $PID > /dev/null 2>&1 echo "Found multiple tunnels. Killed all." done } # Hidden function. Add 'cleanup' as argument to close all the tunnels [ "$1" == "cleanup" ] && reset_tunnel && exit 0 if [ $N_TUNS -eq 0 ] ; then create_tunnel elif [ $N_TUNS -eq 1 ] ; then check_tunnel if [ $? -eq 0 ] ; then echo "Tunnel already up and running" else reset_tunnel create_tunnel fi else reset_tunnel create_tunnel fi if [ $? -eq 0 ] ; then echo "Sock already created on port $SOCK_PORT - just opening SSH shell on $DEST_BOX_HOST" ssh -p$LOC_PORT $DEST_BOX_USER@localhost else # This will open an SSH shell from DEST_BOX *AND* create a sock proxy on port $SOCK_PORT locally # You can use FoxyProxy in your browser to browse the DEST_BOX's network # Just set "localhost", dest port "$SOCK_PORT" and select "Socks Proxy" echo "Created sock on port $SOCK_PORT and ssh'ing on $DEST_BOX_HOST" ssh -D$SOCK_PORT -p$LOC_PORT $DEST_BOX_USER@localhost fi |