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FRAGROUTER(8) System Manager's Manual FRAGROUTER(8) NAME fragrouter - network intrusion detection evasion toolkit SYNOPSIS fragrouter [ -i interface ] [ -p ] [ -g hop ] [ -G hopcount ] ATTACK DESCRIPTION Fragrouter is a program for routing network traffic in such a way as to elude most network intrusion detection systems. Most attacks implemented correspond to those listed in the Secure Net- works ``Insertion, Evasion, and Denial of Service: Eluding Network In- trusion Detection'' paper of January 1998. OPTIONS -i Specify the interface to accept packets on. -p Preserve the entire protocol header in the first fragment. This is useful in bypassing packet filters that deny short IP frag- ments. -g Specify a hop along a loose source routed path. Can be used more than once to build a chain of hop points. -G Positions the "hop counter" within the list of hosts in the path of a source routed packet. Should be a multiple of 4. Can be set past the length of the loose source routed path to implement An- thony Osborne's Windows IP source routing attack of September 1999. The following attack options are mutually exclusive - you may only specify one type of attack to run at a time. -B1 baseline-1: Normal IP forwarding. -F1 frag-1: Send data in ordered 8-byte IP fragments. -F2 frag-2: Send data in ordered 24-byte IP fragments. -F3 frag-3: Send data in ordered 8-byte IP fragments, with one frag- ment sent out of order. -F4 frag-4: Send data in ordered 8-byte IP fragments, duplicating the penultimate fragment in each packet. -F5 frag-5: Send data in out of order 8-byte IP fragments, duplicat- ing the penultimate fragment in each packet. -F6 frag-6: Send data in ordered 8-byte IP fragments, sending the marked last fragment first. -F7 frag-7: Send data in ordered 16-byte IP fragments, preceding each fragment with an 8-byte null data fragment that overlaps the latter half of it. This amounts to the forward-overlapping 16-byte fragment rewriting the null data back to the real at- tack. -T1 tcp-1: Complete TCP handshake, send fake FIN and RST (with bad checksums) before sending data in ordered 1-byte segments. -T3 tcp-3: Complete TCP handshake, send data in ordered 1-byte seg- ments, duplicating the penultimate segment of each original TCP packet. -T4 tcp-4: Complete TCP handshake, send data in ordered 1-byte seg- ments, sending an additional 1-byte segment which overlaps the penultimate segment of each original TCP packet with a null data payload. -T5 tcp-5: Complete TCP handshake, send data in ordered 2-byte seg- ments, preceding each segment with a 1-byte null data segment that overlaps the latter half of it. This amounts to the for- ward-overlapping 2-byte segment rewriting the null data back to the real attack. -T7 tcp-7: Complete TCP handshake, send data in ordered 1-byte seg- ments interleaved with 1-byte null segments for the same connec- tion but with drastically different sequence numbers. -T8 tcp-8: Complete TCP handshake, send data in ordered 1-byte seg- ments with one segment sent out of order. -T9 tcp-9: Complete TCP handshake, send data in out of order 1-byte segments. -C2 tcbc-2: Complete TCP handshake, send data in ordered 1-byte seg- ments interleaved with SYN packets for the same connection para- meters. -C3 tcbc-3: Do not complete TCP handshake, but send null data in or- dered 1-byte segments as if one had occured. Then, complete a TCP handshake with same connection parameters, and send the real data in ordered 1-byte segments. -R1 tcbt-1: Complete TCP handshake, shut connection down with a RST, re-connect with drastically different sequence numbers and send data in ordered 1-byte segments. -I2 ins-2: Complete TCP handshake, send data in ordered 1-byte seg- ments but with bad TCP checksums. -I3 ins-3: Complete TCP handshake, send data in ordered 1-byte seg- ments but with no ACK flag set. -M1 misc-1: Thomas Lopatic's Windows NT 4 SP2 IP fragmentation at- tack of July 1997 (see http://www.dataprotect.com/ntfrag/ for details). This attack has only been implemented for UDP. -M2 misc-2: John McDonald's Linux IP chains IP fragmentation attack of July 1998 (see http://www.dataprotect.com/ipchains/ for de- tails). This attack has only been implement for TCP and UDP. SEE ALSO tcpdump(8), tcpreplay(8), pcap(3), libnet(3) AUTHOR Dug Song, Anzen Computing. The current version is available via HTTP: http://www.anzen.com/research/nidsbench/ BUGS IP options will carry across all fragments of a packet. Fragrouter is not smart enough to determine which IP options are valid only in the first fragment. This is considered a feature, not a bug. :-) Similarly, TCP options will carry across all segments of a split TCP packet - except for null data packets preceding a forward overwrite, which lack any TCP options in order to elude TCP PAWS elimination. Please send bug reports to nidsbench@anzen.com. 26 April 1999 FRAGROUTER(8)
NAME | SYNOPSIS | DESCRIPTION | OPTIONS | SEE ALSO | AUTHOR | BUGS
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