Comment 27 for bug 198884

It looks like this can be triggered with the "dumpcap" tool itself quite easily:
$ sudo dumpcap
works
$ gksu dumpcap
hangs.

If I strace it, it hangs in:
close(3) = 0
socket(PF_PACKET, SOCK_RAW, 768) = 3
ioctl(3, SIOCGIFINDEX, {ifr_name="lo", ifr_index=1}) = 0
ioctl(3, SIOCGIFHWADDR, {ifr_name="eth1", ifr_hwaddr=xx:xx:xx:xx:xx:xx}) = 0
ioctl(3, SIOCGIFINDEX, {ifr_name="eth1", ifr_index=218}) = 0
bind(3, {sa_family=AF_PACKET, proto=0x03, if218, pkttype=PACKET_HOST, addr(0)={0, }, 20) = 0
getsockopt(3, SOL_SOCKET, SO_ERROR, [0], [4]) = 0
close(3) = 0
socket(PF_PACKET, SOCK_RAW, 768) = 3
ioctl(3, SIOCGIFINDEX, {ifr_name="lo", ifr_index=1}) = 0
ioctl(3, SIOCGIFHWADDR, {ifr_name="eth0", ifr_hwaddr=00:xx:xx:xx:xx:xx}) = 0
ioctl(3, SIOCGIFINDEX, {ifr_name="eth0", ifr_index=219}) = 0
bind(3, {sa_family=AF_PACKET, proto=0x03, if219, pkttype=PACKET_HOST, addr(0)={0, }, 20) = 0
getsockopt(3, SOL_SOCKET, SO_ERROR, [0], [4]) = 0
close(3) = 0
socket(PF_PACKET, SOCK_DGRAM, 768) = 3
ioctl(3, SIOCGIFINDEX, {ifr_name="lo", ifr_index=1}) = 0
close(3
...

and then nothing. I wonder if it might be something releated to the stdout, e.g. gksu playing with the buffering options or something similar.