How to get the DNS server address which are specific to each ppp session. For example, I have to ppp sessions each one connected different service provider, how do I find out the DNS server IP address which are assigned by each service provider? In general, the /etc/ppp/resolv.conf file will be overwritten with the new DNS IP address whenever a new ppp session is established. Is there any way how we can maintain separate files for DNS servers for each service provider?
ppp comes with scripts to update resolv.conf for you. Look at /etc/ppp/ip-up and /etc/ppp/ip-up.d/0dns-up. The last one has the rules for updating the resolv.conf file. ($DNS1 and $DNS2 variables).
You can add an ip-up.d script if you want.