Question: When outside our company firewall, I use a script to tunnel via SSH and expose our internal wiki to my OSX machine. Is there a command to temporarily tell OSX to resolve to my local port when the tunnel is set up?

The sequence I'm hoping to use is:

1. open the tunnel
`ssh -f external-proxy.example -L 8001:internal-wiki.example:8000 -N`
2. [DO SOMETHING HERE]
3. typing the URL **internal-wiki.example:8000** in my browser causes it to transparently view **localhost:8001**

Other details:

* I could edit **/etc/hosts** but that would be a persistent change. I want to use this only when outside
* We're not using SSL or certs.

Answer: 
I have a solution for you, wrap your ssh command into a bash script:

```
#!/bin/bash

function control_c {
    echo -en "\n## Caught SIGINT; Clean up /etc/hosts and Exit \n"
    sed -i '' "/internal-wiki/d" /etc/hosts
    exit $?
}

trap control_c SIGINT
trap control_c SIGTERM

(sleep 5; open http://internal-wiki.example:8001 &)&
echo '127.0.0.1 internal-wiki.example' >> /etc/hosts
ssh -L8001:internal-wiki.example:8000 -f external-proxy.example -N

```

Explaining:

1. function that executes the cleanup on Control-C when issued
2. trap Control-C and shutdown
3. sleep, tell osx to open your site, get out of the way (the
ampersand)
4. adds the entry to `/etc/hosts`
5. create the tunnel
6. when you ctrl-c, the functions kicks in and cleans up `/etc/hosts`
with the transient entry
Run a load balancing web server on your Mac balancing between the localhost forwarding and the real address of the wiki configured to prefer the localhost forwarding address. 

When the ssh connection is down the load balancer will notice and direct your
connections to the regular wiki address. 

Configure your web browser to proxy connections for the wiki via the load balancer.

Somewhat of a sledgehammer to crack a nut though.