This is a very quick and very dirty guide to adding support for new capture file formats. If you see any errors or have any improvements, submit patches - free software is a community effort.... To add the ability to read a new capture file format, you have to: add a new WTAP_FILE_ value for the file type to "wiretap/wtap.h"; write an "open" routine that can read the beginning of the capture file and figure out if it's in that format or not, either by looking at a magic number at the beginning or by using some form of heuristic to determine if it's a file of that type (if the file format has a magic number, that's what should be used); write a "read" routine that can read a packet from the file and supply the packet length, captured data length, time stamp, and packet pseudo-header (if any) and data, and have the "open" routine set the "subtype_read" member of the "wtap" structure supplied to it to point to that routine; write a "seek and read" routine that can seek to a specified location in the file for a packet and supply the packet pseudo-header (if any) and data, and have the "open" routine set the "subtype_seek_read" member of the "wtap" structure to point to that routine; write a "close" routine, if necessary (if, for example, the "open" routine allocates any memory), and set the "subtype_close" member of the "wtap" structure to point to it, otherwise leave it set to NULL; add a pointer to the "open" routine to the "open_routines_base[]" table in "wiretap/file_access.c" - if it uses a magic number, put it in the first section of that list, and, if it uses a heuristic, put it in the second section, preferably putting the heuristic routines for binary files before the heuristic routines for text files; add an entry for that file type in the "dump_open_table_base[]" in "wiretap/file_access.c", giving a descriptive name, a short name that's convenient to type on a command line (no blanks or capital letters, please), common file extensions to open and save, a flag if it can be compressed with gzip (currently unused) and pointers to the "can_write_encap" and "dump_open" routines if writing that file is supported (see below), otherwise just null pointers. Wiretap applications typically first perform sequential reads through the capture file and may later do "seek and read" for individual frames. The "read" routine should set the variable data_offset to the byte offset within the capture file from which the "seek and read" routine will read. If the capture records consist of: capture record header pseudo-header (e.g., for ATM) frame data then data_offset should point to the pseudo-header. The first sequential read pass will process and store the capture record header data, but it will not store the pseudo-header. Note that the seek_and_read routine should work with the "random_fh" file handle of the passed in wtap struct, instead of the "fh" file habndle used in the normal read routine. To add the ability to write a new capture file format, you have to: add a "can_write_encap" routine that returns an indication of whether a given packet encapsulation format is supported by the new capture file format; add a "dump_open" routine that starts writing a file (writing headers, allocating data structures, etc.); add a "dump" routine to write a packet to a file, and have the "dump_open" routine set the "subtype_write" member of the "wtap_dumper" structure passed to it to point to it; add a "dump_close" routine, if necessary (if, for example, the "dump_open" routine allocates any memory, or if some of the file header can be written only after all the packets have been written), and have the "dump_open" routine set the "subtype_close" member of the "wtap_dumper" structure to point to it; put pointers to the "can_write_encap" and "dump_open" routines in the "dump_open_table_base[]" entry for that file type. In the wiretap directory, add your source file to CMakelists.txt and your source and header file to Makefile.common.