fragroute8

Usage

Overview

fragroute intercepts, modifies, and rewrites egress traffic destined for the specified host, implementing most of the attacks described in the Secure Networks ``Insertion, Evasion, and Denial of Service: Eluding Network Intrusion Detection'' paper of January 1998.

The options are as follows:

-f file

Read ruleset from the specified file instead of /etc/fragroute.conf.

Unlike fragrouter(8), this program only affects packets originating from the local machine destined for a remote host. Do not enable IP forwarding on the local machine.

Ruleset

fragroute is composed of several modules which enable various configuration directives. Each directive operates on a logical packet queue handed to it by the previous rule.

# string ...

Ruleset comment, no-op.

delay first|last|random ms

Delay the delivery of the first, last, or a randomly selected packet from the queue by ms milliseconds.

drop first|last|random prob-%

Drop the first, last, or a randomly selected packet from the queue with a probability of prob-% percent.

dup first|last|random prob-%

Duplicate the first, last, or a randomly selected packet from the queue with a probability of prob-% percent.

echo string ...

Echo the string argument(s) to standard output.

ip_chaff dup|opt|ttl

Interleave IP packets in the queue with duplicate IP packets containing different payloads, either scheduled for later delivery, carrying invalid IP options, or bearing short time-to-live values.

ip_frag size [old|new]

Fragment each packet in the queue into size-byte IP fragments, preserving the complete transport header in the first fragment. Optional fragment overlap may be specified as old or new, to favor newer or older data.

ip_opt lsrr|ssrr ptr ip-addr ...

Add IP options to every packet, to enable loose or strict source routing. The route should be specified as list of IP addresses, and a bytewise pointer into them (e.g. the minimum ptr value is 4).

ip_ttl ttl

Set the IP time-to-live value of every packet to ttl.

ip_tos tos

Set the IP type-of-service bits for every packet to tos.

order random|reverse

Re-order the packets in the queue randomly, or in reverse.

print

Print each packet in the queue in tcpdump-style format.

tcp_chaff cksum|null|paws|rexmit|seq|syn|ttl

Interleave TCP segments in the queue with duplicate TCP segments containing different payloads, either bearing invalid TCP checksums, null TCP control flags, older TCP timestamp options for PAWS elimination, faked retransmits scheduled for later delivery, out-of-window sequence numbers, requests to re-synchronize sequence numbers mid-stream, or short time-to-live values.

tcp_opt mss|wscale size

Add TCP options to every TCP packet, to set the maximum segment size or window scaling factor.

tcp_seg size [old|new]

Segment each TCP data segment in the queue into size-byte TCP segments. Optional segment overlap may be specified as old or new, to favor newer or older data.

Examples

Fragment all traffic to a Windows host into forward-overlapping 8-byte fragments (favoring older data), reorder randomly, and print to standard output:

	ip_frag 8 old
	order random
	print

Segment all TCP data to a host into forward-overlapping 4-byte segments (favoring newer data), interleave with overwriting, random chaff segments bearing older timestamp options for PAWS elimination, reorder randomly, and print to standard output:

	tcp_seg 4 new
	tcp_chaff paws
	order random
	print

Files

/etc/fragroute.conf

Default configuration ruleset