editcap分割CAP包

-c
Splits the packet output to different files based on uniform packet counts with a maximum of each. Each output file will be created with a suffix -nnnnn, starting with 00000. If the specified number of packets is written to the output file, the next output file is opened. The default is to use a single output file.

-C
Sets the chop length to use when writing the packet data. Each packet is chopped at the packet end by a few bytes of data.

This is useful in the rare case that the conversion between two file formats leaves some random bytes at the end of each packet.

-d
Attempts to remove duplicate packets. The length and MD5 hash of the current packet are compared to the previous four (4) packets. If a match is found, the current packet is skipped. This option is equivalent to using the option -D 5.

-D
Attempts to remove duplicate packets. The length and MD5 hash of the current packet are compared to the previous - 1 packets. If a match is found, the current packet is skipped.

The use of the option -D 0 combined with the -v option is useful in that each packet's Packet number, Len and MD5 Hash will be printed to standard out. This verbose output (specifically the MD5 hash strings) can be useful in scripts to identify duplicate packets across trace files.

The is specifed as an integer value between 0 and 1000000 (inclusive).

NOTE: Specifying large values with large tracefiles can result in very long processing times for editcap.

-w
Attempts to remove duplicate packets. The current packet's arrival time is compared with up to 1000000 previous packets. If the packet's relative arrival time is less than or equal to the of a previous packet and the packet length and MD5 hash of the current packet are the same then the packet to skipped. The duplicate comparison test stops when the current packet's relative arrival time is greater than .

The is specifed as seconds[.fractional seconds].

The [.fractional seconds] component can be specified to nine (9) decimal places (billionths of a second) but most typical trace files have resolution to six (6) decimal places (millionths of a second).

NOTE: Specifying large values with large tracefiles can result in very long processing times for editcap.

NOTE: The -w option assumes that the packets are in chronological order. If the packets are NOT in chronological order then the -w duplication removal option may not identify some duplicates.

-E
Sets the probabilty that bytes in the output file are randomly changed. Editcap uses that probability (between 0.0 and 1.0 inclusive) to apply errors to each data byte in the file. For instance, a probability of 0.02 means that each byte has a 2% chance of having an error.

This option is meant to be used for fuzz-testing protocol dissectors.

-F
Sets the file format of the output capture file. Editcap can write the file in several formats, editcap -F provides a list of the available output formats. The default is the libpcap format.

-A
Saves only the packets whose timestamp is on or after start time. The time is given in the following format YYYY-MM-DD HH:MM:SS

-B
Saves only the packets whose timestamp is on or before stop time. The time is given in the following format YYYY-MM-DD HH:MM:SS

-h
Prints the version and options and exits.

-i
Splits the packet output to different files based on uniform time intervals using a maximum interval of each. Each output file will be created with a suffix -nnnnn, starting with 00000. If packets for the specified time interval are written to the output file, the next output file is opened. The default is to use a single output file.

-r
Reverse the packet selection. Causes the packets whose packet numbers are specified on the command line to be written to the output capture file, instead of discarding them.

-s
Sets the snapshot length to use when writing the data. If the -s flag is used to specify a snapshot length, packets in the input file with more captured data than the specified snapshot length will have only the amount of data specified by the snapshot length written to the output file.

This may be useful if the program that is to read the output file cannot handle packets larger than a certain size (for example, the versions of snoop in Solaris 2.5.1 and Solaris 2.6 appear to reject Ethernet packets larger than the standard Ethernet MTU, making them incapable of handling gigabit Ethernet captures if jumbo packets were used).

-t
Sets the time adjustment to use on selected packets. If the -t flag is used to specify a time adjustment, the specified adjustment will be applied to all selected packets in the capture file. The adjustment is specified as [-]seconds[.fractional seconds]. For example, -t 3600 advances the timestamp on selected packets by one hour while -t -0.5 reduces the timestamp on selected packets by one-half second.

This feature is useful when synchronizing dumps collected on different machines where the time difference between the two machines is known or can be estimated.

-T
Sets the packet encapsulation type of the output capture file. If the -T flag is used to specify an encapsulation type, the encapsulation type of the output capture file will be forced to the specified type. editcap -T provides a list of the available types. The default type is the one appropriate to the encapsulation type of the input capture file.

Note: this merely forces the encapsulation type of the output file to be the specified type; the packet headers of the packets will not be translated from the encapsulation type of the input capture file to the specified encapsulation type (for example, it will not translate an Ethernet capture to an FDDI capture if an Ethernet capture is read and '-T fddi' is specified). If you need to remove/add headers from/to a packet, you will need od(1)/text2pcap(1).

-v
Causes editcap to print verbose messages while it's working.

Use of -v with the de-duplication switches of -d, -D or -w will cause all MD5 hashes to be printed whether the packet is skipped or not.

每个文件中有20480000个包方法
editcap -c 20480000 148.cap result.cap
 

example:

To see more detailed description of the options use:
    editcap -h

To shrink the capture file by truncating the packets at 64 bytes and writing it as Sun snoop file use:
    editcap -s 64 -F snoop capture.pcap shortcapture.snoop

To delete packet 1000 from the capture file use:
    editcap capture.pcap sans1000.pcap 1000

To limit a capture file to packets from number 200 to 750 (inclusive) use:
    editcap -r capture.pcap small.pcap 200-750

To get all packets from number 1-500 (inclusive) use:
    editcap -r capture.pcap first500.pcap 1-500
 or
    editcap capture.pcap first500.pcap 501-9999999

To exclude packets 1, 5, 10 to 20 and 30 to 40 from the new file use:
    editcap capture.pcap exclude.pcap 1 5 10-20 30-40

To select just packets 1, 5, 10 to 20 and 30 to 40 for the new file use:
    editcap -r capture.pcap select.pcap 1 5 10-20 30-40

To remove duplicate packets seen within the prior four frames use:
    editcap -d capture.pcap dedup.pcap

To remove duplicate packets seen within the prior 100 frames use:
    editcap -D 101 capture.pcap dedup.pcap

To remove duplicate packets seen equal to or less than 1/10th of a second:
    editcap -w 0.1 capture.pcap dedup.pcap

To display the MD5 hash for all of the packets (and NOT generate any real output file):
    editcap -v -D 0 capture.pcap /dev/null
 or on Windows systems
    editcap -v -D 0 capture.pcap NUL

To introduce 5% random errors in a capture file use:
  editcap -E 0.05 capture.pcap capture_error.pcap

转自：http://www.cnblogs.com/lovemo1314/archive/2010/09/27/1837074.html