TCPREWRITE(1)

NAME
tcprewrite - Rewrite the packets in a pcap file.

SYNOPSIS
tcprewrite [-flag [value]]... [--opt-name [[=| ]value]]...

All arguments must be options.

DESCRIPTION
This manual page briefly documents the tcprewrite command. Tcprewrite is a tool to rewrite packets stored in pcap(3) file format, such as crated by tools such as tcpdump(1) and ethereal(1). Once a pcap file has had it's packets rewritten, they can be replayed back out on the network using tcpreplay(1). tcprewrite currently supports reading the following DLT types:

DLT_C_HDLC aka Cisco HDLC

DLT_EN10MB aka Ethernet

DLT_LINUX_SLL aka Linux Cooked Socket

DLT_RAW aka RAW IP

DLT_NULL aka BSD Loopback

DLT_LOOP aka OpenBSD Loopback

DLT_IEEE802_11 aka 802.11a/b/g

DLT_IEEE802_11_RADIO aka 802.11a/b/g with Radiotap headers Please see the --dlt option for supported DLT types for writing. The packet editing features of tcprewrite which distinguish between "client" and "server" traffic requires a tcpprep(1) cache file. For more details, please see the Tcpreplay Manual at: http://tcpreplay.synfin.net/trac/wiki/manual

OPTIONS

-r string, --portmap=string
    Rewrite TCP/UDP ports. This option may appear up to 1 times.

    Specify a list of comma delimited port mappingings 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. Example:
        --portmap=80:8000,8080:80

-s number, --seed=number
    Randomize src/dst IP addresses w/ given seed. This option may appear up to 1 times. This option takes an integer number as its argument.

    Causes the source and destination IP 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.

-N string, --pnat=string
    Rewrite IP addresses using pseudo-NAT. This option may appear up to 2 times. This option must not appear in combination with any of the following options: srcipmap.

    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 rewriten using the second netblock as a mask against the high order bits. Example:
        --pnat=192.168.0.0/16:10.77.0.0/16,172.16.0.0/12:10.1.0.0/24

-S string, --srcipmap=string
    Rewrite source IP addresses using pseudo-NAT. This option may appear up to 1 times. This option must not appear in combination with any of the following options: pnat.

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

-D string, --dstipmap=string
    Rewrite destination IP addresses using pseudo-NAT. This option may appear up to 1 times. This option must not appear in combination with any of the following options: pnat.

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

-e string, --endpoints=string
    Rewrite IP addresses to be between two endpoints. This option may appear up to 1 times. This option must appear in combination with the following options: cachefile.

    Takes a pair of colon delimited IP addresses which will be used to rewrite all traffic to appear to be between the two IP's. Example:
        --endpoints=172.16.0.1:172.16.0.2

-b, --skipbroadcast
    Skip rewriting broadcast/multicast IP's.

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

-C, --fixcsum
    Force recalculation of IP/TCP/UDP checksums.

    Causes each IP packet to have it's checksums recalcualted and fixed. Automatically enabled for packets modified with --seed, --pnat, --endpoints or --fixlen.

-m number, --mtu=number
    Override default MTU length (1500 bytes). This option may appear up to 1 times. This option takes an integer number as its argument. The value of number is constrained to being:
    in the range  1 through MAXPACKET

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

--mtu-trunc
    Truncate packets larger then specified MTU. This option may appear up to 1 times.

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

-E, --efcs
    Remove Ethernet checksums (FCS) from end of frames.

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

--ttl=string
    Modify the IPv4 TTL.

    Allows you to modify the TTL of all the IPv4 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

--tos=number
    Set the IPv4 TOS/DiffServ/ECN byte. This option may appear up to 1 times. This option takes an integer number as its argument. The value of number is constrained to being:
    in the range  0 through 255

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

-F string, --fixlen=string
    Pad or truncate packet data to match header length. This option may appear up to 1 times.

    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 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

--skipl2broadcast
    Skip rewriting broadcast/multicast Layer 2 addresses.

    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.

--dlt=string
    Override output DLT encapsulation. This option may appear up to 1 times.

    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

    user User specified Layer 2 header and DLT type

--enet-dmac=string
    Override destination ethernet MAC addresses. This option may appear up to 1 times.

    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

--enet-smac=string
    Override source ethernet MAC addresses. This option may appear up to 1 times.

    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

--enet-vlan=string
    Specify ethernet 802.1q VLAN tag mode. This option may appear up to 1 times.

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

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

--enet-vlan-tag=number
    Specify the new ethernet 802.1q VLAN tag value. This option may appear up to 1 times. This option must appear in combination with the following options: enet-vlan. This option takes an integer number as its argument. The value of number is constrained to being:
    in the range  0 through 4095

--enet-vlan-cfi=number
    Specify the ethernet 802.1q VLAN CFI value. This option may appear up to 1 times. This option must appear in combination with the following options: enet-vlan. This option takes an integer number as its argument. The value of number is constrained to being:
    in the range  0 through 1

--enet-vlan-pri=number
    Specify the ethernet 802.1q VLAN priority. This option may appear up to 1 times. This option must appear in combination with the following options: enet-vlan. This option takes an integer number as its argument. The value of number is constrained to being:
    in the range  0 through 7

--hdlc-control=number
    Specify HDLC control value. This option may appear up to 1 times. This option takes an integer number as its argument.

    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.

--hdlc-address=number
    Specify HDLC address. This option may appear up to 1 times. This option takes an integer number as its argument.

    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.

--user-dlt=number
    Set output file DLT type. This option may appear up to 1 times. This option takes an integer number as its argument.

    Set the DLT value of the output pcap file.

--user-dlink=string
    Rewrite Data-Link layer with user specified data. This option may appear up to 2 times.

    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

-d number, --dbug=number
    Enable debugging output. This option may appear up to 1 times. This option takes an integer number as its argument. The value of number is constrained to being:
    in the range  0 through 5
    The default number for this option is:
     0

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

-i string, --infile=string
    Input pcap file to be processed. This option may appear up to 1 times.

-o string, --outfile=string
    Output pcap file. This option may appear up to 1 times.

-c string, --cachefile=string
    Split traffic via tcpprep cache file. This option may appear up to 1 times.

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

-v, --verbose
    Print decoded packets via tcpdump to STDOUT. This option may appear up to 1 times.

-A string, --decode=string
    Arguments passed to tcpdump decoder. This option may appear up to 1 times. This option must appear in combination with the following options: verbose.

    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.

--fragroute=string
    Parse fragroute configuration file. This option may appear up to 1 times.

    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.

--fragdir=string
    Which flows to apply fragroute to: c2s, s2c, both. This option may appear up to 1 times.

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

--skip-soft-errors
    Skip writing packets with soft errors. This option may appear up to 1 times.

    In some cases, packets can't 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.

-V, --version
    Print version information.

-h, --less-help
    Display less usage information and exit.

-H, --help
    Display usage information and exit.

-!, --more-help
    Extended usage information passed thru pager.

- [rcfile], --save-opts[=rcfile]
    Save the option state to rcfile. The default is the last configuration file listed in the OPTION PRESETS section, below.

- rcfile, --load-opts=rcfile, --no-load-opts
    Load options from rcfile. The no-load-opts form will disable the loading of earlier RC/INI files. --no-load-opts is handled early, out of order.

OPTION PRESETS
Any option that is not marked as not presettable may be preset by loading values from configuration ("RC" or ".INI") file(s). The homerc file is "$$/", unless that is a directory. In that case, the file ".tcprewriterc" is searched for within that directory.

SEE ALSO
tcpdump(1), tcpprep(1), tcpreplay(1)

AUTHOR
Copyright 2004-2008 Aaron Turner For support please use the tcpreplay-users@lists.sourceforge.net mailing list. The latest version of this software is always available from: http://tcpreplay.synfin.net/

Released under the Free BSD License.

This manual page was AutoGen-erated from the tcprewrite option definitions.