Mine

auto ppp0
iface ppp0 inet ppp
provider dsl-provider
pre-up /sbin/ifconfig eth0 up
post-up /etc/ppp/ip-up.d/0cil
post-down /etc/ppp/ip-down.d/00mm


orion:~# run-parts --list /etc/ppp/ip-down.d/
/etc/ppp/ip-down.d//0000usepeerdns
/etc/ppp/ip-down.d//00mm
/etc/ppp/ip-down.d//0clampmss
/etc/ppp/ip-down.d//0dns-down
/etc/ppp/ip-down.d//0pppstatus
/etc/ppp/ip-down.d//fetchmail
/etc/ppp/ip-down.d//snort