High, On Tue, 7 Aug 2001, David Morris wrote:
> I know this is something I have seen somewhere (and it is probably something > right in front of my eyes). But I have just setup a cable modem that uses > dhclient to grab it's IP. Every once in a while the cable modem will flake > out > and then it is unusable - until I sit down and either physically reboot it, > or > (I've figured this out) release the IP and drop the NIC then reconnect the > card and the dhclient. > > What I want is a script I can run as a cron job (every 15 minutes or so) that > will check to see if the network is usable or not. If the modem has flaked > out > on me, it will bring it down and then keep trying to bring it up until it > succeeds. (Oh and it would be nice to have it send me a little email telling > me what it did - that's not asking too much is it? :). > > Like I said, I know this has got to be somewhere, but I can't find it. Can > someone point to where it is laid out for me or maybe put together a little > script fragment that will do the checking for me? > It is really very simple. Add these lines to /etc/crontab: 0 * * * * root /bin/ping -c 2 -i 5 213.10.33.89 > /dev/null || /etc/init.d/adsl restart 15 * * * * root /bin/ping -c 2 -i 5 213.10.33.89 > /dev/null || /etc/init.d/adsl restart 30 * * * * root /bin/ping -c 2 -i 5 213.10.33.89 > /dev/null || /etc/init.d/adsl restart 45 * * * * root /bin/ping -c 2 -i 5 213.10.33.89 > /dev/null || /etc/init.d/adsl restart where 213.10.33.89 is the closest ip address and /etc/init.d/adsl is your connection script. The big prob is to find the proper IP address. It is not ok if you use the IP of your modem, because Linux uses a shortcut then. I think it is quite safe to take the first ip after your network, i.e. do a traceroute to somewhere and write down the first ip address after your network (this is probably your isp's). Do this with some sessions in a couple of days. If you are sure enough that the address does not change, use that. Also note that if you have a slow connection you have to play with the ping respond times. Perhaps you could even setup a traceroute kind of script in stead of ping. Greetz, Sebastiaan
