Pair Sessions Script Adding more security (automatically timeout sudo, append the command to each ssh key

README.md

My script for pair sessions on my box.

What it does

• downloads the appropriate ssh keys from github
• copies the appropriate 'ssh pair@your-external-ip' command to your clipboard (see Note #1)
• sets up the tmux session
• cleans up the session, and the keys after it's done

How to use

First, brew install tmux

Then you type:

pair-session marksim

After that, just hit paste into your pair's chat window and voila, they ssh in and are automatically connected via tmux.

Issues

1. If you are running linux, you can easily alias pbcopy and pbpaste like so: http://whereswalden.com/2009/10/23/pbcopy-and-pbpaste-for-linux/

pair-session.sh

#!/bin/sh
if [[ $# -eq 0 ]] ; then
  echo "Usage: $0 [tmux-session-name] github-username [github-user-name [...]]"
  exit 0
fi

# *************************** SETUP ****************************
# Find the LAN IP, the External IP, and the pair users's group
INTERFACE=$(netstat -rn -f inet | grep default | awk '{print $6}') 
LAN_IP=$(ipconfig getifaddr $INTERFACE) 
EXTERNAL_IP=$(dig +short myip.opendns.com @resolver1.opendns.com)
GROUP=$(id -g pair)

if [ -e /tmp/$1 ]; then
  SESSION=$1
else
  SESSION='pairing'
fi

sudo mkdir -p ~pair/.ssh
sudo chown pair:$GROUP ~pair/.ssh
sudo touch ~pair/.ssh/authorized_keys
# Download the public keys to the pair user
for username in "$@"
do
  SSH_KEYS_STRING=$(curl https://github.com/$username.keys)
  sudo bash -c "echo '$SSH_KEYS_STRING' >> ~pair/.ssh/authorized_keys" 
done
TMUX=$(echo `which tmux` | sed -e 's/\\/\\\\/g' -e 's/\//\\\//g' -e 's/&/\\\&/g')
sudo sed -i -e "s/^/command=\"$TMUX -S \/tmp\/$SESSION attach -t $SESSION\",no-port-forwarding,no-X11-forwarding,no-agent-forwarding /" ~pair/.ssh/authorized_keys
sudo chown pair:$GROUP ~pair/.ssh/authorized_keys

# Copy the ssh command to the clipboard - OS X specific
echo "ssh pair@$EXTERNAL_IP" | pbcopy
sudo -k

# ************************** PAIRNG ****************************
function setup_session {
  tmux -S /tmp/$SESSION new -ds $SESSION && chgrp $GROUP /tmp/$SESSION && tmux -S /tmp/$SESSION attach -t $SESSION
}
tmux -S /tmp/$SESSION attach -t $SESSION || setup_session

# ************************** CLEANUP ***************************
# Cleanup keys
sudo rm -f ~pair/.ssh/authorized_keys
sudo -k

Great script, Mark. I made a small change as I didn't like the idea of leaving port 22 open to the public internet. I know it's not a great measure of protection, but obfuscating the ssh port seemed like a very easy way to hopefully avoid unwanted attention from scanners during the pair session.

https://gist.github.com/kmeister2000/5935441

The script depends on sudo useradd pair having been run