Dealing with MTU problems Sometimes the maximum size of a frame you can send on an interface MTU is smaller then some packets you need to send. Similar to --fixlen, this option will truncate data in packets from Layer 3 and above to be no larger then the MTU.
This is historical material from my old site, but as I have just bumped into a page that linked to it, I thought I would republish it. I have not verified that this material is still accurate. Takes a pair of comma deliminated ethernet MAC addresses which will replace the destination MAC address of outbound packets.
The default number for this option is: Due to library constraints fragroute may or may not enabled in your binary. Both can be set using this plugin: This can obviously cause problems later on when you try replaying the traffic.
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. This issue is not particular to Vyatta, or even to Linux, but rather seems to be a common issue, particularly with Intel cards but also with others, such as the Marvel Yukon.
The following would cause all traffic to have a destination MAC of Since IP fragmentation is done at the IP layer, we use a value smaller then the MTU in this case assuming for ethernet to make sure we have enough room for the ethernet and IPv4 headers.
Pad the packets with 0x Due to library constraints fragroute may or may not enabled in your binary. Be sure to quote the arguments like: Normally, tcpreplay will skip these packets completely, but you have a few other options: Both can be set using this plugin: Specify a floating point value to modify the packet replay speed.
It allows you to map IP addresses in one subnet to IP addresses in another subnet.
Depending on the device type that will be processing the traffic, the application data may or may not be important, but having a full packet may be. We'll assume the client is Note that by removing the packet from the output pcap file, hence you should not re-use a tcpprep cache file with the resulting file since it will no longer match the pcap file.
You can specify multiple CIDR pairs and use the --pnat flag twice if you use a cache file. Since IP fragmentation is done at the IP layer, we use a value smaller then the MTU in this case assuming for ethernet to make sure we have enough room for the ethernet and IPv4 headers.
When specifying IPv6 addresses, wrap the address in hard brackets like so: Note that this feature only handles IP headers and ARP messages; it does not modify application data which may contain your original IP address as well.
Truncate packets to the MTU length default bytes: Each source and destination subnet is expressed in CIDR notation, and needn't be the same size.
Mon Jan 17 The value of number is constrained to being: By using the --fixcsum flag, you can force tcprewrite to fix the checksums. The following would cause all traffic to have a destination MAC of FF or multicast first octet is odd.
Make sure you have enough free RAM to store the entire pcap file s in memory or the system will swap and performance will suffer. When enabling a layer 3 rewrite rule, tcprewrite will automagically re-calculate checksums for you, so there is no need to pass --fixcsum.
Hence, you should only use this if you know know that your OS provides the FCS when reading raw packets. tcprewrite. TOC(depth=2, manual, tcpreplay, tcpliveplay, tcpprep, tcprewrite, tcpbridge, tcpcapinfo, flowreplay, commonargs, usage, FAQ)? Overview. Specify ethernet q VLAN tag mode.
This option may appear up to 1 times. Allows you to rewrite ethernet frames to add a q header to standard ethernet headers or. tcprewrite − Rewrite the packets in a pcap file. SYNOPSIS. Allows you to rewrite ethernet frames to add a q header to standard ethernet headers or remove the q VLAN tag information.
add Rewrites the existing ethernet header as an q VLAN header. Jun 19, · I tried it and addded VLAN id with tcprewrite (ok), set up a vlan-tagged interface virbr tagged with VLAN id (also ok), then tried tcpreplay to virbr - but no luck.
It says Fatal Error: Invalid interface name/alias: virbr In fact it won't even let me use the buddy virbr0 interface either - it has disappeared from the. [Humbledown highlights] VLAN tag stripping in Virtualbox (actually, Intel NICs et al.) February 01, This is historical material from my old site, but as I have just bumped into a page that linked to it, I thought I would republish it.
The tcprewirte cannot do vlan add/delete for each client or server. e.g. the stream from A to B using vlan tagfrom B to A using vlan tagTcprewrite add vlan tag