I have a problem with ppp-2.4.3. As soon as I add the option:

active-filter 'outbound and not icmp[0] == 3 and not tcp[13] & 4 !=0'

pppd quits immediately without any message. When omitting this option,
everything is working as expected. Is there a way to see what is going
wrong there?

Kernel: Linux (with CONFIG_PPP_FILTER)
PPP: 2.4.3 (compiled with filter support)
libpcap: 0.9.4

This is how I call pppoe:
/usr/bin/setsid /usr/sbin/pppd pty '/usr/sbin/pppoe
-p /var/run/pppoe.conf-pppoe.pid.pppoe -I eth1 -T 80 -U -m 1412 '
noipdefault noauth default-asyncmap defaultroute hide-password nodetach
mtu 1492 mru 1492 noaccomp nodeflate nopcomp novj novjccomp user xxx
lcp-echo-interval 20 lcp-echo-failure 3 file /etc/ppp/options.pppoe

options.pppoe contains the active-filter line.