Frequent timeout

Matus UHLAR - fantomas uhlar at
Fri Sep 7 07:02:23 UTC 2018

>On Thu, Sep 6, 2018 at 5:56 PM John W. Blue < at> wrote:
>> So that file is full of nothing but queries and no responses which, sadly, is useless.
>> Run:
>> tcpdump -s0 -n -i eth0 port domain -w /tmp/domaincapture.pcap
>> You don't need all of the extra stuff because -s0 captures the full packet.

On 06.09.18 18:42, Alex wrote:
>This is the command I ran to produce the pcap file I sent:
># tcpdump -s0 -vv -i eth0 -nn -w domain-capture-eth0-090518.pcap udp
>dst port domain

and that is the problem. "dst port domain" captures packets going to DNS
servers, not responses coming back.

"-vv" and "-nn" are useless when producing packet capture and "-s0" is
default for some time. I often add "-U" so file is flushed wich each packet.

you can strip incoming queries by using filter

"(src host 68.195.XXX.45 and dst port domain) or (src port domain and dst host 68.195.XXX.45)"

>I should also mention that, while eth0 is the physical device, there
>is a bridge set up to support virtual machines (none of which were
>active). Hopefully that's not the reason! (real IP obscured).

not the reason, but using "-i br0" could be safer then.

Note that the IP was seen in packet capture you have published, not needed
to hide it now.

Matus UHLAR - fantomas, uhlar at ;
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