how to run script after internet connection

OkoSanto · 05-26-2009, 04:49 AM

Hi,

I would like to mount my afs account at the university on my home laptop automatically. The problem is that my uni won't allow afs access if I use ssh public/private keypair authentication. That means there is no way around entering the password for my account when I want to mount the remote afs filesystem. (That seems to exclude doing it with autofs+sshfs.)

As a workaround, I've created a script using expect, that enters my password for me. It looks something like:

Code:

#!/usr/bin/expect
spawn kinit -A -f login@HOST
expect "login@HOST's Password:"
send "password\r"
expect eof

(yes, I'm aware storing my password in a script like this isn't very safe

)
If I run this script myself from shell, it works as it should: I get a kerberos token and I can ssh to my uni account, or use sshfs to mount my afs account locally, without having to enter my password again.

My question now is, how can I make this script run automatically once I've established an internet connection? I use wifi at home, so generally it takes until about a minute after booting until my connection is established. This would exclude running the above script at startup?

I read somewhere that I could put the script at /etc/dhcp3/dhclient-exit-hooks.d/ to have it run automatically once an ip address has been assigned, but that doesn't seem to work (I boot, connect to the internet, but no token). Is there a log somewhere I could check to see if the script runs/generates errors?

I'm really new to all this, so I don't really have a clue of how these things fit together. All information/hints/workarounds you can give me will be highly appreciated!

twantrd · 05-26-2009, 10:06 PM

I don't know what the "/etc/dhcp3/dhclient-exit-hooks.d/" directory does so I can't help ya out there. To test it out, write a bash script that writes out a file to /tmp/test.log (or whatever you want to name it) and place it in that directory. Restart your laptop and check if the file exists or not.

You said it takes about 1 minute to grab an IP. Since I'm not fluent in expect, I would write a simple wrapper script in bash and place it in your startup scripts. Something like:

Code:

#!/bin/bash

sleep 80 #sleeps for a minute and 20 seconds
expect /path/to/your/expect_script

-twantrd

OkoSanto · 05-28-2009, 04:21 AM

Ok, I've figured it out! The first issue is that I'm using Networkmanager to manage my wifi connections. With Networkmanager, the scripts in /etc/dhcp3/dhclient-exit-hooks.d/ are no longer run.

Instead, the Networkmanager daemon runs scripts at /etc/Networkmanager/dispatcher.d/ . Networkmanager passes the variables INTERFACE and ACTION to the script, and you can test for ACTION == 'pre-up' 'up' 'down' 'post-down' to perform different tasks depending on the state of your connection.

Then I had some more trouble to get the syntax correct (your hint of writing a test.log file to see wether the script was actually run, helped to track down the problems, so thanks a lot!)

By calling the expect script above from a bash script in .../dispatcher.d/ my root gets a kerberos token, and I can then automount my afs folder using autofs and sshfs. Which is exactly what I was looking for!

Strange I couldn't find this dispatcher rightaway when googling for "run script after internet connection" etc...