276, "CUSTOM_MY_PROTO", DLT_CUSTOM ,
: This format is used by Linux kernels to capture packets from multiple interfaces simultaneously (e.g., using tcpdump -i any ) or from interfaces that do not have a standard Ethernet header .
You used a or nRF Sniffer to capture BLE packets. The output file is a .pcap with DLT 276. You try opening it in:
If you already have a 276 pcap file, you can attempt to convert it using editcap (part of the Wireshark suite) or tcprewrite , though upgrading is more reliable. pcap: network type 276 unknown or unsupported Meaning LINKTYPE_LINUX_SLL2 (Modern Linux cooked capture) Cause Wireshark < 3.3.0 or old libpcap Fix Upgrade Wireshark/TShark to 3.4+ -pcap network type 276 unknown or unsupported-
The stock repositories for older LTS versions often provide outdated Wireshark builds. Use the Official Wireshark PPA to get the latest stable version:
To fix the error immediately, you must or use a tool like editcap to translate the encapsulation type back to a standard format. Root Cause Analysis
Because the tool can’t identify the "start" of the packet (the Layer 2 header), it cannot decode the IP (Layer 3) or TCP/UDP (Layer 4) data inside. How to Fix the "Unknown or Unsupported" Error 1. Update Your Software 276, "CUSTOM_MY_PROTO", DLT_CUSTOM , : This format is
Every packet in a pcap or pcap-ng file begins with a . This header describes the encapsulation of the packet—Ethernet, Wi-Fi, Linux cooked capture, Bluetooth, etc. The pcap file format stores a numeric code for this encapsulation, known as the DLT (Data Link Type) , defined in the pcap.h header file and standardized by the libpcap library.
If you have a small capture and know the packet payloads are raw IP or UDP, you can change the DLT with a hex editor:
If you encounter this, rest assured it is not a corrupted file, but rather a . You try opening it in: If you already
xxd -c 1 -p capture.pcap | awk '...' # (complex; see advanced documentation)
Before solving the error, you must understand the underlying architecture of the pcap (Packet Capture) format.