Specify a list of comma delimited port mappings consisting of colon delimited port number pairs. Each colon delimited port pair consists of the port to match followed by the port number to rewrite.

Examples:

    --portmap=80:8000 --portmap=8080:80    # 80->8000 and 8080->80
    --portmap=8000,8080,88888:80           # 3 different ports become 80
    --portmap=8000-8999:80                 # ports 8000 to 8999 become 80
    

Causes the source and destination IPv4/v6 addresses to be pseudo randomized but still maintain client/server relationships. Since the randomization is deterministic based on the seed, you can reuse the same seed value to recreate the traffic.

Takes a comma delimited series of colon delimited CIDR netblock pairs. Each netblock pair is evaluated in order against the IP addresses. If the IP address in the packet matches the first netblock, it is rewritten using the second netblock as a mask against the high order bits.

IPv4 Example:

    --pnat=192.168.0.0/16:10.77.0.0/16,172.16.0.0/12:10.1.0.0/24
    

    --pnat=[2001:db8::/32]:[dead::/16],[2001:db8::/32]:[::ffff:0:0/96]
    

Works just like the --pnat option, but only affects the source IP addresses in the IPv4/v6 header.

Works just like the --pnat option, but only affects the destination IP addresses in the IPv4/v6 header.

Takes a pair of colon delimited IPv4/v6 addresses which will be used to rewrite all traffic to appear to be between the two IP addresses.

IPv4 Example:

    --endpoints=172.16.0.1:172.16.0.2
    

    --endpoints=[2001:db8::dead:beef]:[::ffff:0:0:ac:f:0:2]
    

greater than or equal to 1
    

Change all TCP sequence numbers, and related sequence-acknowledgement numbers. They will be shifted by a random amount based on the provided seed.

By default --seed, --pnat and --endpoints will rewrite broadcast and multicast IPv4/v6 and MAC addresses. Setting this flag will keep broadcast/multicast IPv4/v6 and MAC addresses from being rewritten.

Causes each IPv4/v6 packet to have their checksums recalculated and fixed. Automatically enabled for packets modified with --seed, --pnat, --endpoints or --fixlen.

in the range  1 through MAX_SNAPLEN
    

Override the default 1500 byte MTU size for determining the maximum padding length (--fixlen=pad) or when truncating (--mtu-trunc).

Similar to --fixlen, this option will truncate data in packets from Layer 3 and above to be no larger then the MTU.

Note, this option is pretty dangerous! We do not actually check to see if a FCS actually exists in the frame, we just blindly delete the last 4 bytes. Hence, you should only use this if you know know that your OS provides the FCS when reading raw packets.

Allows you to modify the TTL/Hop Limit of all the IPv4/v6 packets. Specify a number to hard-code the value or +/-value to increase or decrease by the value provided (limited to 1-255).

Examples:

    --ttl=10
    --ttl=+7
    --ttl=-64
    

in the range  0 through 255
    

Allows you to override the TOS (also known as DiffServ/ECN) value in IPv4.

in the range  0 through 255
    

Allows you to override the IPv6 Traffic Class field.

in the range  0 through 1048575
    

Allows you to override the 20bit IPv6 Flow Label field. Has no effect on IPv4 packets.

Packets may be truncated during capture if the snaplen is smaller then the packet. This option allows you to modify the packet to pad the packet back out to the size stored in the IPv4/v6 header or rewrite the IP header total length to reflect the stored packet length.

pad Truncated packets will be padded out so that the packet length matches the IPv4 total length

trunc Truncated packets will have their IPv4 total length field rewritten to match the actual packet length

del Delete the packet

greater than or equal to 0
    

This fuzzing was designed as to test layer 7 protocols such as voip protocols. It modifies randomly 1 out of X packets (where X = --fuzz-factor) in order for stateful protocols to cover more of their code. The random fuzzing actions focus on data start and end because it often is the part of the data application protocols base their decisions on.

Possible fuzzing actions list: * drop packet * reduce packet size * edit packet Bytes: * Not all Bytes have the same probability of appearance in real life. Replace with 0x00, 0xFF, or a random byte with equal likelihood. * Not all Bytes have the same significance in a packet. Replace the start, the end, or the middle of the packet with equal likelihood. * do nothing (7 out of 8 packets)

greater than or equal to 1
    

Sets the ratio of for --fuzz-seed option. By default this value is 8, which means 1 in 8 packets are modified by fuzzing. Note that this ratio is based on the random number generated by the supplied fuzz seed. Therefore by default you cannot expect that exactly every eighth packet will be modified.

By default, editing Layer 2 addresses will rewrite broadcast and multicast MAC addresses. Setting this flag will keep broadcast/multicast MAC addresses from being rewritten.

By default, no DLT (data link type) conversion will be made. To change the DLT type of the output pcap, select one of the following values:

enet Ethernet aka DLT_EN10MB

hdlc Cisco HDLC aka DLT_C_HDLC

jnpr_eth Juniper Ethernet DLT_C_JNPR_ETHER

pppserial PPP Serial aka DLT_PPP_SERIAL

user User specified Layer 2 header and DLT type

Takes a pair of comma deliminated ethernet MAC addresses which will replace the destination MAC address of outbound packets. The first MAC address will be used for the server to client traffic and the optional second MAC address will be used for the client to server traffic.

Example:

    --enet-dmac=00:12:13:14:15:16,00:22:33:44:55:66
    

Takes a pair of comma deliminated ethernet MAC addresses which will replace the source MAC address of outbound packets. The first MAC address will be used for the server to client traffic and the optional second MAC address will be used for the client to server traffic.

Example:

    --enet-smac=00:12:13:14:15:16,00:22:33:44:55:66
    

Allows you to rewrite ethernet MAC addresses of packets. It takes comma delimited pair or MACs address and rewrites all occurrences of the first MAC with the value of the second MAC. Example:

    --enet-subsmac=00:12:13:14:15:16,00:22:33:44:55:66
    

Allows you to randomize ethernet MAC addresses of packets, mostly like what --seed option does for IPv4/IPv6 addresses.

in the range  1 through 6
    

Keep some bytes untouched when usinging --enet-mac-seed option.

Allows you to rewrite ethernet frames to add a 802.1q header to standard 802.3 ethernet headers or remove the 802.1q VLAN tag information.

add Adds an 802.1q VLAN header to the existing 802.3 ethernet header. If a VLAN header already exists, a new VLAN header is added outside of the existing header.

Note that you will be allowed to run this option multiple times to create more than 2 VLAN headers, however those packets will be valid. At most you should have 2 X 802.1q VLAN tags, or outer an 802.1ad and an inner 802.1q VLAN tag.

del Rewrites the existing 802.1q VLAN header as an 802.3 ethernet header

in the range  0 through 4095
    

in the range  0 through 1
    

in the range  0 through 7
    

Allows you to specify the protocol of the added VLAN tags.

802.1q Specifies that 802.1q VLAN headers are to be added. This is the default.

802.1ad Specifies that 802.1ad Q-in-Q VLAN headers are to be added. To make valid packets, input packets must already have 802.1q VLAN headers.

The Cisco HDLC header has a 1 byte "control" field. Apparently this should always be 0, but if you can use any 1 byte value.

The Cisco HDLC header has a 1 byte "address" field which has two valid values:

0x0F Unicast

0xBF Broadcast
You can however specify any single byte value.

Set the DLT value of the output pcap file.

Provide a series of comma deliminated hex values which will be used to rewrite or create the Layer 2 header of the packets. The first instance of this argument will rewrite both server and client traffic, but if this argument is specified a second time, it will be used for the client traffic.

Example:

    --user-dlink=01,02,03,04,05,06,00,1A,2B,3C,4D,5E,6F,08,00
    

in the range  0 through 5
    

If configured with --enable-debug, then you can specify a verbosity level for debugging output. Higher numbers increase verbosity.

Use tcpprep cache file to split traffic based upon client/server relationships.

When enabling verbose mode (-v) you may also specify one or more additional arguments to pass to tcpdump to modify the way packets are decoded. By default, -n and -l are used. Be sure to quote the arguments so that they are not interpreted by tcprewrite. Please see the tcpdump(1) man page for a complete list of options.

Enable advanced evasion techniques using the built-in fragroute(8) engine. See the fragroute(8) man page for more details. Important: tcprewrite does not support the delay, echo or print commands.

Apply the fragroute engine to packets going c2s, s2c or both when using a cache file.

In some cases, packets can not be decoded or the requested editing is not possible. Normally these packets are written to the output file unedited so that tcpprep cache files can still be used, but if you wish, these packets can be suppressed.

One example of this is 802.11 management frames which contain no data.