tcprewrite(1) User Commands tcprewrite(1)NAMEtcprewrite - Rewrite the packets in a pcap file.
SYNOPSIStcprewrite [-flags] [-flag [value]] [--option-name[[=| ]value]]
All arguments must be options.
DESCRIPTION
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
DLT_JUNIPER_ETHER aka Juniper Encapsulated Ethernet
DLT_PPP_SERIAL aka PPP over Serial
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://tcpre‐
play.appneta.com
OPTIONS-r string, --portmap=string
Rewrite TCP/UDP ports. This option may appear up to 9999 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.
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
-s number, --seed=number
Randomize src/dst IPv4/v6 addresses w/ given seed. This option
may appear up to 1 times. This option must not appear in combi‐
nation with any of the following options: fuzz-seed. This
option takes an integer number as its argument.
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.
-N string, --pnat=string
Rewrite IPv4/v6 addresses using pseudo-NAT. This option may
appear up to 2 times. This option must not appear in combina‐
tion 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 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
IPv6 Example:
--pnat=[2001:db8::/32]:[dead::/16],[2001:db8::/32]:[::ffff:0:0/96]
-S string, --srcipmap=string
Rewrite source IPv4/v6 addresses using pseudo-NAT. This option
may appear up to 1 times. This option must not appear in combi‐
nation with any of the following options: pnat.
Works just like the --pnat option, but only affects the source
IP addresses in the IPv4/v6 header.
-D string, --dstipmap=string
Rewrite destination IPv4/v6 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 destina‐
tion IP addresses in the IPv4/v6 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 combina‐
tion with the following options: cachefile.
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
IPv6 Example:
--endpoints=[2001:db8::dead:beef]:[::ffff:0:0:ac:f:0:2]
-b, --skipbroadcast
Skip rewriting broadcast/multicast IPv4/v6 addresses.
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.
-C, --fixcsum
Force recalculation of IPv4/TCP/UDP header checksums.
Causes each IPv4/v6 packet to have their checksums recalculated
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 max‐
imum 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 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 pack‐
ets.
--ttl=string
Modify the IPv4/v6 TTL/Hop Limit.
Allows you to modify the TTL/Hop Limit of all the IPv4/v6 pack‐
ets. 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 argu‐
ment. 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.
--tclass=number
Set the IPv6 Traffic Class 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 IPv6 Traffic Class field.
--flowlabel=number
Set the IPv6 Flow Label. 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 1048575
Allows you to override the 20bit IPv6 Flow Label field. Has no
effect on 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/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
--fuzz-seed=number
Fuzz 1 in X packets. Edit bytes, length, or emulate packet drop.
This option takes an integer number as its argument. The value
of number is constrained to being:
greater than or equal to 0
The default number for this option is:
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 like‐
lyhook
* 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)
--fuzz-factor=number
Set the Fuzz 1 in X packet ratio (default 1 in 8 packets). This
option must appear in combination with the following options:
fuzz-seed. This option takes an integer number as its argument.
The value of number is constrained to being:
greater than or equal to 1
The default number for this option is:
8
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 genereated by the
supplied fuzz seed. Therefore by default you cannot expect that
exactly every eighth packet will be modified.
--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 broad‐
cast/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 fol‐
lowing values:
enet Ethernet aka DLT_EN10MB
hdlc Cisco HDLC aka DLT_C_HDLC
jnpr_ether Juniper Ethernet DLT_C_JNPR_ETHER
pppserial PPP Serial aka DLT_PPP_SERIAL
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-subsmac=string
Substitute MAC addresses. This option may appear up to 9999
times.
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
--enet-mac-seed=number
Randomize MAC addresses. This option may appear up to 1 times.
This option must not appear in combination with any of the fol‐
lowing options: enet-smac, enet-dmac, enet-subsmac. This option
takes an integer number as its argument.
Allows you to randomize ethernet MAC addresses of packets,
mostly like what --seed option does for IPv4/IPv6 addresses.
--enet-mac-seed-keep-bytes=number
Randomize MAC addresses. This option may appear up to 1 times.
This option must appear in combination with the following
options: enet-mac-seed. This option takes an integer number as
its argument. The value of number is constrained to being:
in the range 1 through 6
Keep some bytes untouched when usinging --enet-mac-seed option.
--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 ether‐
net 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 con‐
strained 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 con‐
strained 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 con‐
strained 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 ver‐
bosity level for debugging output. Higher numbers increase ver‐
bosity.
-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 pack‐
ets 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 fra‐
groute(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. This option must appear in combina‐
tion with the following options: cachefile.
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 not be decoded or the requested edit‐
ing 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
Pass the extended usage information through a pager.
--save-opts [=cfgfile]
Save the option state to cfgfile. The default is the last con‐
figuration file listed in the OPTION PRESETS section, below.
The command will exit after updating the config file.
--load-opts=cfgfile, --no-load-opts
Load options from cfgfile. The no-load-opts form will disable
the loading of earlier config/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 load‐
ing 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.
FILES
See OPTION PRESETS for configuration files.
EXIT STATUS
One of the following exit values will be returned:
0 (EXIT_SUCCESS)
Successful program execution.
1 (EXIT_FAILURE)
The operation failed or the command syntax was not valid.
66 (EX_NOINPUT)
A specified configuration file could not be loaded.
70 (EX_SOFTWARE)
libopts had an internal operational error. Please report it to
autogen-users@lists.sourceforge.net. Thank you.
AUTHORS
Copyright 2013-2017 Fred Klassen - AppNeta Copyright 2000-2012 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.appneta.com/
COPYRIGHT
Copyright (C) 2000-2017 Aaron Turner and Fred Klassen all rights
reserved. This program is released under the terms of the GNU General
Public License, version 3 or later.
BUGS
Please send bug reports to: tcpreplay-users@lists.sourceforge.net
NOTES
This manual page was AutoGen-erated from the tcprewrite option defini‐
tions.
tcprewrite 16 May 2017 tcprewrite(1)
