Merging trace files with Mergecap

You can use Mergecap to merge two or more trace files into one file. The basic syntax is as follows:

mergecap –w <outfile.pcapng>  infile1.pcapng   infile2.pcapng  …

For example:

mergecap –w merged.pacap   source1.pcapng   source2.pcapng    source3.pcapng

One useful option you sometimes may want to use in Mergecap (and several of the other command-line utilities) is –s <snaplen>. This will truncate the packets at the specified length past the start of each frame, resulting in a smaller file; a typical value for <snaplen> is 128 bytes:

mergecap –w merged_trimmed.pcapng  -s 128  source1.pcapng  source2.pcapng

Mergecap batch file

If the capture files you want to merge have a variety of naming formats, you can create a MergeTraces.bat file containing the following Windows batch commands:

@echo off
cls
echo MergeTraces.bat
echo.
echo Merges multiple packet trace files with a .pcapng extension into one .pcapng file
echo.
echo Usage: Copy MergeTraces...