Script to setup multiple SSH tunnels in a reliable way for use with FoxyProxy or other SOCKS-aware clients

init-tunnels.sh

#!/usr/bin/env bash
#
# Use to setup numerous various tunnels to SSH servers, useful with ssh config blocks like those below
# for each host, with incrementing port numbers for each - then configure FoxyProxy etc to use the unique
# port for each host you want to tunnel out of.
#
# Thanks to tecknicaltom <[email protected]> for the initial idea behind tying this all together.
#
# Host host_alpha
#	  IdentityFile ~/.ssh/id_ecdsa-$USER-host_alpha-<remote_hostname>-<key_gen_year>-<key_gen_month>
#	  DynamicForward localhost:4504
#
# Host host_bravo
#	  IdentityFile ~/.ssh/id_ecdsa-$USER-host_bravo-<remote_hostname>-<key_gen_year>-<key_gen_month>
#	  DynamicForward localhost:4505
#
# Example FoxyProxy config XML block (import/export):
#
#     <proxy name="host_alpha" id="12345" notes="localhost:4504/socks (SSH)" enabled="true" color="#AFBD31" mode="manual" autoconfMode="pac" lastresort="false">
#      <manualconf host="localhost" port="4504" socksversion="5" isSocks="true"/>
#      <autoconf url="" reloadPac="false" loadNotification="true" errorNotification="true" autoReload="false" reloadFreqMins="60" disableOnBadPAC="true"/>
#      <matches>
#        <match enabled="true" name="*" isRegex="false" pattern="*" reload="true" autoReload="false" isBlackList="false" isMultiLine="false" fromSubscription="false" caseSensitive="false"/>
#      </matches>
#    </proxy>
#
#     <proxy name="host_bravo" id="54321" notes="localhost:4505/socks (SSH)" enabled="true" color="#AFBD31" mode="manual" autoconfMode="pac" lastresort="false">
#      <manualconf host="localhost" port="4505" socksversion="5" isSocks="true"/>
#      <autoconf url="" reloadPac="false" loadNotification="true" errorNotification="true" autoReload="false" reloadFreqMins="60" disableOnBadPAC="true"/>
#      <matches>
#        <match enabled="true" name="*" isRegex="false" pattern="*" reload="true" autoReload="false" isBlackList="false" isMultiLine="false" fromSubscription="false" caseSensitive="false"/>
#      </matches>
#    </proxy>
#
#
# SSH Options
# -N Do not execute a remote command.  This is useful for just forwarding ports (protocol version 2 only).
# -f Requests ssh to go to background just before command execution.  This is useful if ssh is going to ask
#    for passwords or passphrases, but the user wants it in the background.  This implies -n.
# -n (implied from -f, above) Redirects stdin from /dev/null (actually, prevents reading from stdin).
#    This must be used when ssh is run in the background.
# -q Quiet mode.  Causes most warning and diagnostic messages to be suppressed.
ssh_cli_options="-Nfq -oControlMaster=no -oControlPath=none -oControlPersist=no"

# AutoSSH options (see man page for autossh for all environment variable information)
export AUTOSSH_GATETIME=0
export AUTOSSH_POLL=30

# Hosts to connect to/setup tunnels for, one per line
hosts_list="${HOME}/.config/scripts/init-tunnels"
if [ ! -r "$hosts_list" ]; then
	echo "[FATAL] Can't read $hosts_list - ensure it exists and contains one host per line." >&2
	exit 1
fi

hosts=$(cat "$hosts_list")

# Connect to each host with the specified options
connection_count=0

for host in $hosts; do
	# No monitor port (needed sometimes in weird environments)
	#ssh_cmd="autossh -M 0"

	# Choose a monitor port off of a base and 10 away from the previous one
	ssh_cmd="autossh -Nf -M $((48004 + (connection_count += 10))) $ssh_cli_options"

	$ssh_cmd $host

	if [ 0 -eq $? ]; then
		echo -n "[INFO]  Tunnel established: $host"
		socks_port=$(grep "^Host.*${host}" ~/.ssh/config -A 5 \
			| grep "DynamicForward" \
			| head -n 1 | awk -F ':' '{print $NF}')
		if [ -n "$socks_port" ]; then
			echo ", SOCKS listener: $socks_port"
		else
			echo
		fi
	else
		echo "[ERROR] Tunnel FAILED ($?): $host" >&2
	fi
done