TCPBRIDGE(1) Programmer's Manual TCPBRIDGE(1)
NAME
tcpbridge - Bridge network traffic across two interfaces
SYNOPSIS
tcpbridge [-flag [value]]... [--opt-name [[=| ]value]]...
All arguments must be options.
tcpbridge is a tool for selectively briding network traffic across two interfaces and optionally modifying the packets in betweeen
DESCRIPTION
This manual page briefly documents the tcpbridge command. The basic operation of tcpbridge is to be a network bridge between two subnets.
All packets received on one interface are sent via the other.
Optionally, packets can be edited in a variety of ways according to your needs.
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 IPv4/v6 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 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 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.
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 combina-
tion 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 com-
bination with any of the following options: pnat.
Works just like the --pnat option, but only affects the destination 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 combination
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's.
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 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 argu-
ment. 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/v6 TTL/Hop Limit.
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
--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.
--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
--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 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 infor-
mation.
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, --intf1=string
Primary interface (listen in uni-directional mode). This option may appear up to 1 times.
-I string, --intf2=string
Secondary interface (send in uni-directional mode). This option may appear up to 1 times.
-u, --unidir
Send and receive in only one direction. This option may appear up to 1 times.
Normally, tcpbridge will send and receive traffic in both directions (bi-directionally). However, if you choose this option, traf-
fic will be sent uni-directionally.
--listnics
List available network interfaces and exit.
-L number, --limit=number
Limit the number of packets to send. 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:
greater than or equal to 1
The default number for this option is:
-1
By default, tcpbridge will send packets forever or until Ctrl-C. Alternatively, you can specify a maximum number of packets to
send.
-M string, --mac=string
MAC addresses of local NIC's. This option may appear up to 2 times.
tcpbridge does not support detecting the MAC addresses of the local network interfaces under Windows. Please specify both MAC
addresses of the interfaces used in the bridge: -M <intf1 mac> -M <intf2 mac>
-x string, --include=string
Include only packets matching rule. This option may appear up to 1 times. This option must not appear in combination with any of
the following options: exclude.
Override default of sending all packets stored in the capture file and only send packets which match the provided rule. Rules can
be one of:
S:<CIDR1>,... - Source IP must match specified CIDR(s)
D:<CIDR1>,... - Destination IP must match specified CIDR(s)
B:<CIDR1>,... - Both source and destination IP must match specified CIDR(s)
E:<CIDR1>,... - Either IP must match specified CIDR(s)
P:<LIST> - Must be one of the listed packets where the list corresponds to the packet number in the capture file.
--include=P:1-5,9,15,72-
would send packets 1 thru 5, the 9th and 15th packet, and packets 72 until the end of the file
F:'<bpf>' - BPF filter. See the tcpdump(8) man page for syntax.
-X string, --exclude=string
Exclude any packet matching this rule. This option may appear up to 1 times. This option must not appear in combination with any
of the following options: include.
Override default of sending all packets stored in the capture file and only send packets which do not match the provided rule.
Rules can be one of:
S:<CIDR1>,... - Source IP must not match specified CIDR(s)
D:<CIDR1>,... - Destination IP must not match specified CIDR(s)
B:<CIDR1>,... - Both source and destination IP must not match specified CIDR(s)
E:<CIDR1>,... - Either IP must not match specified CIDR(s)
P:<LIST> - Must not be one of the listed packets where the list corresponds to the packet number in the capture file.
--exclude=P:1-5,9,15,72-
would drop packets 1 thru 5, the 9th and 15th packet, and packets 72 until the end of the file
-P, --pid
Print the PID of tcpbridge at startup.
-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 follow-
ing 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 like: --verbose="-axxx" so that they are not inter-
preted by tcpbridge. The following arguments are vaild:
[ -aAeNqRStuvxX ]
[ -E spi@ipaddr algo:secret,... ]
[ -s snaplen ]
-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 ".tcpbridgerc" is searched for within that directory.
SIGNALS
tcpbridge understands the following signals:
SIGUSR1 Suspend tcpbridge
SIGCONT Restart tcpbridge
SEE ALSO
tcpdump(1), tcpprep(1), tcprewrite(1), tcpreplay(1)
BUGS
tcpbridge can only send packets as fast as your computer's interface, processor and system bus will allow.
Connecting both interfaces to the same subnet may create a broadcast storm and take down the network. Improper use of the packet editing
functions may have other undefined and possible negative consequences.
Some operating systems by default do not allow for forging source MAC addresses. Please consult your operating system's documentation and
the tcpreplay FAQ if you experiance this issue.
AUTHOR
Copyright 2000-2008 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 tcpbridge option definitions.
(tcpbridge ) 2009-06-25 TCPBRIDGE(1)