SSH magic tricks

tron.sh

#!/bin/bash

# Should we connect via IPv4 or IPv6?
if ping -c 1 ipv6.google.com &> /dev/null
then
	SERVER="tron6"
else
	SERVER="tron"
fi

# Media shares and mount points
SMB="//tron/Tron"
SMB_MOUNT="/mnt/tron/smb"
SSHFS="/home/nticompass"
SSHFS_MOUNT="/mnt/tron/ssh"

# Access to internal machines
USERNAME="nticompass"
HYPERCUBE="hypercube"
ROUTER="enigma"

# Script variables
SOCKET="/tmp/$SERVER.ssh"
PID=""

# SSH can do a bunch of fun stuff in "master mode"
# https://en.wikibooks.org/wiki/OpenSSH/Cookbook/Tunnels#Adding_or_Removing_Tunnels_within_a_Multiplexed_Connection
# https://en.wikibooks.org/wiki/OpenSSH/Cookbook/Multiplexing

# Sets the $PID variable to the pid of the ssh process (if it exists)
checkConnection(){
	PID=""
	file $SOCKET > /dev/null
	if [ $? -eq 0 ]; then
		SSHCONN=`ssh -S $SOCKET -O check $SERVER 2>&1`
		if [ $? -eq 0 ]; then
			PID=`echo $SSHCONN | awk '{print $3}'`
		fi
	fi
}

# If the connection is *not* runningm then open it in master mode
# and throw it into the background
openConnection(){
	checkConnection
	if [ "$PID" == "" ]; then
		ssh -S $SOCKET -MfnNTY $SERVER
		PID=`ssh -S $SOCKET -O check $SERVER 2>&1 | awk '{print $3}'`
	fi
}

# Close open ssh connections
# Also unmounts any network shares
closeConnection(){
	checkConnection
	if [ "$PID" != "" ]; then
		# Make sure to unmount everything before closing the connection
		MOUNT=`mount | grep "$SMB"`
		if [ $? -eq 0 ]; then
			sudo umount $SMB_MOUNT
		fi

		MOUNT=`mount | grep "$SERVER:$SSHFS"`
		if [ $? -eq 0 ]; then
			fusermount -u $SSHFS_MOUNT
		fi

		ssh -S $SOCKET -O exit $SERVER
	fi
}

# If ran without parameters, then just open a shell
if [ $# -ne 1 ]; then
	openConnection
	ssh -S $SOCKET -Y $SERVER
	echo "Make sure to run '`basename $0` exit'"
	exit 0
fi

# Otherwise, figure out what to do
case $1 in
	# Mount Tron's SMB via SSH tunnel
	"mount")
		openConnection
		ssh -S $SOCKET -O forward -L 10139:localhost:139 -L 10445:localhost:445 $SERVER
		sudo mount -t cifs $SMB $SMB_MOUNT -o ip=127.0.0.1,port=10445,user=nticompass,ro,fsc
		;;
	# Unmount tron SMB
	"umount")
		sudo umount $SMB_MOUNT
		checkConnection
		if [ "$PID" != "" ]; then
			ssh -S $SOCKET -O cancel -L 10139:localhost:139 -L 10445:localhost:445 $SERVER
		fi
		;;
	# Mount tron via SSHFS (sharing the connection)
	"sshfs")
		openConnection
		sshfs $SERVER:$SSHFS $SSHFS_MOUNT -o follow_symlinks -o ControlPath=$SOCKET
		;;
	# Unmount SSHFS
	"fusermount")
		checkConnection
		if [ "$PID" != "" ]; then
			fusermount -u $SSHFS_MOUNT
		fi
		;;
	# Fowrard ports on tron
	# 8000 => Apache
	# 9091 => Transmission
	"forward")
		openConnection
		ssh -S $SOCKET -O forward -L 8000:localhost:80 -L 9091:localhost:9091 $SERVER
		;;
	# Close the above ports
	"unforward")
		checkConnection
		if [ "$PID" != "" ]; then
			ssh -S $SOCKET -O cancel -L 8000:localhost:80 -L 9091:localhost:9091 $SERVER
		fi
		;;
	# SSH to my desktop, hypercube
	"hypercube")
		openConnection
		ssh -S $SOCKET -O forward -L 2221:$HYPERCUBE:22 $SERVER
		ssh -p 2221 $USERNAME@localhost
		ssh -S $SOCKET -O cancel -L 2221:$HYPERCUBE:22 $SERVER
		;;
	# Forward ports to the router's admin page
	# 8888
	"router")
		openConnection
		ssh -S $SOCKET -O forward -L 8888:$ROUTER:80 $SERVER
		;;
	# Close connection to the router
	"norouter")
		checkConnection
		if [ "$PID" != "" ]; then
			ssh -S $SOCKET -O cancel -L 8888:$ROUTER:80 $SERVER
		fi
		;;
	# Just open the connection, *without* a shell
	"open")
		checkConnection
		if [ "$PID" == "" ]; then
			openConnection
			echo "SSH connection to $SERVER opened $PID"
		else
			echo "SSH connection *already* open: $SERVER $PID"
		fi
		;;
	# Kill the connection and unmount everything
	"exit")
		closeConnection
		;;
	# Display information about the connection and mounted shares
	"status")
		checkConnection
		if [ "$PID" != "" ]; then
			echo "SSH Tunnel: $SERVER $PID"

			MOUNT=`mount | grep "$SMB"`
			if [ $? -eq 0 ]
			then
				echo "SMB Mount: mounted ($SMB_MOUNT)"
			else
				echo "SMB Mount: not mounted"
			fi

			MOUNT=`mount | grep "$SERVER:$SSHFS"`
			if [ $? -eq 0 ]
			then
				echo "SSHFS Mount: mounted ($SSHFS_MOUNT)"
			else
				echo "SSHFS Mount: not mounted"
			fi
		else
			echo "SSH Tunnel: not running"
		fi
		;;
	# Some basic help
	*)
		echo "Usage: `basename $0` [command]"
		exit 1
		;;
esac

Replace ping google with ip -6 a | grep inet6 | grep -Ev "(fe80|::1)"?