PS: Stefan, have you tried your patch on wheezy? For me, running patched arpwatch without "-F" parameter crashes it with:
segfault at 0 ip 00007fcc33e7ac21 sp 00007fff9743e428 error 4 in libc-2.13.so[7fcc33dfb000+17d000] -- To UNSUBSCRIBE, email to debian-bugs-dist-requ...@lists.debian.org with a subject of "unsubscribe". Trouble? Contact listmas...@lists.debian.org