hey gang, Im trying to do something I've done repeatedly with static external ip addresses but now that I have a external dhcp address things have gone a little off.
What I used to do was mv /etc/resolv.conf to /etc/resolv.conf.dnsmasq and tell dnsmasq to read this file instead of /etc/resolv.conf then I would edit /etc/resolv.conf to point the machine back to itself. This way during normal operation the dhcp server ping, ssh, etc to the same machines by hostname that the clients all did. no biggie Enter a dhcp based external interface /etc/resolv.conf is rewritten from time to time as my ISP uses a set of DNS servers and selects the least busy one to give out for load balancing reasons. There are lots of tutorials on how to get /etc/resolv.conf to NOT get rewritten, but if the ISP changes it on purpose, not rewriting the file is not an option. so, I came up with the idea of creating an extra file called /etc/resolv.conf.perm for the permanant /etc/resolv.conf to reside. Then as part of dhclient-exit-hooks, I would check if /etc/resolv.conf had been rewritten some way and if it did, move the .conf file to .conf.dnsmasq and then copy the .conf.perm into .conf then I would have to send dnsmasq a signal (a SIGHUP if I read the docs correctly) Then I need the script to do something strange, I want it to upload a file to my isp's webhosting account so that my public ip address is available via a simple grep of a downloaded .html file I already know how to script an ftp session, so that part is easy. I have several questions... 1) according to dnsmasq documentation a SIGHUP will cause all the config files to re re-read and it will also re-read /etc/resolv.conf if the no-poll option is set. Am I reading this correctly? Is there a way to ask dnsmasq to just re-read the resolv file without having to reload everything? 2) I'm not convinced that dhclient-exit-hooks is the right place for this, but I cant think of another. There are lots of google hits on errors with dhclient-exit-hooks not running. Not to mention that I dont yet understand when the various things happen that dhclient-script asks for. (like "Is /etc/resolv.conf created before or after the exit-hooks-script is run?" or "What about one of the interface specific scripts that dhclient-script executes at different places in the process?" or "Is the value of the new IP available to a dhclient-exit-hooks script so I could just reference the variable, or do I have to look it up on my own?" If someone would be so kind as to help straighten me out with a pointer to a good primer, or something like that I would be grateful. Is there a better way/place to do what I want to do? 3) if anyone has done anything like this, and wouldn't mind sharing, I'd love to see a reasonably active script that really does some stuff. Thanks all for the time, and I apologize for the parts of this that are related, but maybe off topic As a way of saying thanks I would like to contribute the script for public use when its done. Simon, you think there is room for something like this in /contrib?
