Hello, list
I have an adsl connection, started by pppd. I tell pppd to use my /etc/resolv.conf by commenting the line "usepeerdns". But after some time, resolv.conf gets changed. These are my configuration files:

### provider
# Minimalistic default options file for DSL/PPPoE connections
noipdefault
defaultroute
replacedefaultroute
hide-password
lcp-echo-interval 30
lcp-echo-failure 4
noauth
persist
# mtu 1492
# usepeerdns
plugin rp-pppoe.so eth0
user "my user"

### options
asyncmap 0
auth
crtscts
lock
hide-password
modem
proxyarp
lcp-echo-interval 30
lcp-echo-failure 4
noipx

Who keeps changing my /etc/resolv.conf? In case it matters, I'm using Debian Sarge.

Very likely in this case what is happening is that your system is doing a DHCP renew. When it does that, it runs the /etc/dhclient-script, which calls /sbin/resolvconf. This in turn queries the DHCP server of your ISP and rewrites resolv.conf.

is there a parameter you can pass to dhclient so that it doesn't rewrite resolv.conf?

Set up a static ip.

I think this is the easiest solution: make sure /etc/resolv.conf contains exactly what you need and then:

chattr +i /etc/resolv.conf

wil make it "immutable"