So far, we need to use GUI to properly register a new custom dissector (DLT_USER (DLT_USER table in Edit->Preferences). Instead of this, which files should I modify to make the same done without GUI? I've found dlt_users dlt_users file in .../AppData/Roaming/Wireshark directory. However this is not the only place I should update because Wireshark doesn't use new dissector anyway. anyway.