On Dec 13, 2010, at 7:48 PM, Levan, Jerry wrote:
>
> Anyway last week I learned that MacOSX client has all of the software
> needed for running a VPN and found a tutorial that explained how to
> set the rascal up.
>
> It noted the problem with dynamic dns addresses and suggested several
> sites that can 'solve' the problem.
>
> I decided that I would reinvent the wheel using the hardware at hand.
>
> My external IP does not change very often so an instantaneous response
> was not necessary.
>
> My solution was simple and did not involve installing any background
> daemons and registering for another account somewhere else in the
> world.
>
> A one line crontab entry:
>
> 0 6-22/4 * * * snmpwalk -Ov -OQ -c public router ipAdEntAddr | mail -s "IP
> Address" [email protected]
>
> You can adjust the frequency of the mail to your paranoia level.
>
> The cronjob sends the list of ip addresses of my airport extreme base station
> to one
> of my mail accounts. It is perfectly clear which of the IPs is the external
> IP of the
> router.
>
> When the router ip changes a quick cut from the mail and paste on my off the
> local net devices will
> point the vpn client to the new address.
>
> Again the url of the tutorial for setting up the VPN:
> http://blog.theilluminatedengineer.com/?p=136
>
> The comments offer additional clues.
>
> Task complete!
>
> Jerry
>
I thought I might try to send email only when the router IP changes...
Here is the shell script that I am fiddling with...
***********************************************
#!/bin/sh
#
# New file: Dec 14, 2010
# Send mail to me if the router IP list changes
# Jerry LeVan
#
old='/tmp/ip.old'
new='/tmp/ip.new'
# get the current ip list of the router
snmpwalk -Ov -OQ -c public router ipAdEntAddr | sort > $new
# check to set if the old ip file exists
if [[ -a $old ]]
then
# old file exists
if ( diff $old $new > /dev/null )
then
# echo they are the same do nothing
exit 0
else
# echo they are diff
cp $new $old
# echo sending notification
mail -s "Router IP Has Changed" [email protected] < $new
fi
else
# old file did not exist
cp $new $old
# echo old did not exist sending notification
mail -s "Router IP " [email protected] < $new
fi
*********************************************
I am executing this file every 10 minutes with a cron table entry:
0-59/10 * * * * /usr/local/bin/checkip.sh
Jerry_______________________________________________
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