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ohrwurm is an RTP fuzzer. features some SIP parsing and RTCP suppressing.
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ohrwurm-0.1 - an RTP fuzzer

(c) 2006 by Matthias Wenzel


type "make", hit return.
report errors to ohrwurm/at/mazzoo/dot/de
ohrwurm requires libpcap.

before starting ohrwurm you need to run arpspoof. arpspoof is a part of the
dsniff package from
Say you want to fuzz the RTP communication between two boxes A and B in your
LAN, with the IPs and .
Now on a third box e.g. start arpspoof twice (in two terminals):


on the same box start ohrwurm with the IP addresses of A and B:
ohrwurm -a -b

Now start a SIP based audio call between A and B. The RTP stream will be
fuzzed. When you're done press CTRL-C in the terminals.
Other options can be seen when running ohrwurm without any arguments.

ohrwurm is german and translates to earwig. So it's something nasty you don't
get rid of easily. Literally translated ohrwurm means earworm.

As of August 2006 ohrwurm broke the following applications/transports:
 - linphonec 1.10 / iLBC (stops sending RTP, no crash)
 - linphonec 1.10 / iLBC (re-negotiates PCMA via SIP, but continues sending
 - Fritz! box 7050 / iLBC (stops sending RTP, no crash)
 - Cisco 7905 crashes with arpspoof alone :(

please report anything ohrwurm broke to ohrwurm/at/mazzoo/dot/de, even if it
was a famous packet sniffer ;)

 - fuzzing:
   - reorder/drop/inject packets
   - change packet length
 - save packets in pcap(tcpdump) format
 - support variable length IP headers
 - support variable length RTP headers
 - support SIP ports other than 5060
 - support multiple calls
 - do we really need to memcpy() eack packet?
 - figure out local mac address differently (ifr)
 - fill ow.rawsock_sa.sll_halen=ETH_ALEN (required??)
 - fill ow.rawsock_sa.sll_addr according to packet(7) (required??)
 - support unidirectional fuzzing
 - support RTCP fuzzing
 - support other media types than "audio" ("video", "application", "data" and
   "control", as per rfc2327), e.g. "m=application 32416 udp"
 - do arpspoof ourself
 - non-LAN, GW and router operation

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