From a report on the help forum:
> segfault while calling dump_open
> Delete By: Shehjar Tikoo (shehjar) - 2007-07-10 19:24
> Hi
>
> Python2.4 crashes with a segfault while calling the dump_open method.
....
> I am using a P4 machine with Debian etch.
https://sourceforge.net/forum/message.php?msg_id=4406974
dump_open can not be called before self->pcap has been initialized by calling some of the open_* functions.
It's a lack of sanity check in both pylibpcap and libpcap. Just use open_offline(filename) instead.
Program received signal SIGSEGV, Segmentation fault.
[Switching to Thread 0xb7cc16c0 (LWP 16579)]
pcap_dump_open (p=0x0, fname=0xb7c62bc4 "msndump.1") at ./savefile.c:1416
1416 linktype = dlt_to_linktype(p->linktype);
(gdb) up
#1 0xb8038512 in pcapObject_dump_open (self=0x879d7f8, fname=0xb7d26bc4 "msndump.1") at pcap_interface.c:132
132 self->pcap_dumper = pcap_dump_open(self->pcap, fname);
(gdb) inspect self->pcap
$1 = (pcap_t *) 0x0
Thanks for the extra investigation, kristjanbb. I've added more sanity checking to pylibpcap so you should get a nice Python exception now instead of a crash.