## AutoSSH – a Reverse Proxy Alternative

This document is best read printed out on paper.
1
Overview
I recently added another apache server to an existing infrastructure, and
I wanted it to be accessible under a similar IP as another server. Due
to the complexity of the website, it was not possible to simply do a reverse
proxy without knowing the correct settings (e.g. X-Forwarded for). Instead,
AutoSSH was used. In the end, I accessed a new port on the existing IP.
2
Work Log
Ok, I’m going to get right to the configs that I used. You want the tool, you
don’t need to know all the details.
2.1
Crontab
Here is the crontab script I used. I put this in /etc/crontab, so it has root
after the times. I only use /etc/crontab, as it’s easier to manage.

* * * * * root pgrep autossh > /dev/null || \
/usr/local/bin/autosshzm/autosshzm.sh

then it will try the next command. (—— is an OR). Put the bash script
wherever you want.
2.2
Bash Script
This script is obviously what the crontab calls.

#!/bin/bash
logger ” /usr/local/bin/autosshzm script started.”
#source $HOME/.bash_profile #not needed. source$HOME/.keychain/$HOSTNAME-sh logger ” /usr/local/bin/autosshzm sourced.” autossh -L 0.0.0.0:2:localhost:80 -f user@ipaddress sleep 31536000 &> /var/log/autosshzm/autosshzm.log 1#autossh -M 0 -o “ServerAliveInterval 30” -o “ServerAliveCountMax 3” -L 0.0.0.0:2:localhost:80 user@ipaddress &> /var/log/autosshzm/autosshzm.log logger “auto ssh ran” Note that the second autossh does not work, as it’s missing the sleep and the -f command. 1 In order for this to work, you’ll also need the following commands: apt-get install keychain autossh There were some more setup steps required for keychain… From stackex- change: 25 keychain solves this in a painless way. It’s in the repos for Debian/Ubuntu: sudo apt-get install keychain and perhaps for many other distros (it looks like it originated from Gentoo). This program will start an ssh-agent if none is running, and provide shell scripts that can be sourced and connect the current shell to this particular ssh-agent. For bash, with a private key named id_rsa, add the following to your .profile: keychain –nogui id_rsa This will start an ssh-agent and add the id_rsa key on the first login after reboot. If the key is passphrase-protected, it will also ask for the passphrase. No need to use unprotected keys anymore! For subsequent logins, it will recognize the agent and not ask for a passphrase again. Also, add the following as a last line of your .bashrc: 1 Figuring this kind of stuff out can take about an hour. 2. ~/.keychain/$HOSTNAME-sh
This will let the shell know where to reach the SSH agent managed
by keychain. Make sure that .bashrc is sourced from .profile.
However, it seems that cron jobs still don’t see this. As a
remedy, include the line above in the crontab, just before
* * * * * . ~/.keychain/\$HOSTNAME-sh; your-actual-command

The only thing that I needed to do here was
keychain –nogui id rsa
The rest of it (notes about crontab) was not required.

3
What Did NOT Work
Here’s some things I tried that did not work.

• https://github.com/obfusk/autossh-init – This init script, didn’t do
much for me. Remember, I’m stuck with systemd in Ubuntu 19.04… 2
• Reverse proxy with Apache – As I said, my website 3 was too complex,
and I didn’t want to go down that rabbit hole.
• Starting AutoSSH in rc.local. Didn’t work.

2
The scourge of deleting software history. Keep backwards compatibility at ALL COSTS, developers.
3
Some people might call it a web application. I will not.
3

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