A pentester used a Nordic nRF52840 Dongle to capture BLE pairing traffic between a smart lock and a phone. When they tried to load the pcap into an older version of Wireshark on a locked-down corporate laptop, they got error 276. They used tshark from a portable Wireshark 4.0 USB installation—no admin rights needed.
tcprewrite --dlt=enet --infile=input.pcap --outfile=output.pcap Use code with caution.
Depending on your use case, choose one of the following solutions.
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(Note: You would need to have the header class defined according to IBM's specifications.) 4. Check for Corruption
A network engineer received a pcap from a remote site that claimed to be "Ethernet" but file command reported "pcap: DLT 276". The remote script had a bug: pcap_open_dead() was called with the wrong DLT due to an uninitialized variable. They fixed the capture script and re-ran the test.
This error comes from packet-processing tools (tcpdump/libpcap, Wireshark, tshark, Scapy, etc.) when they read a pcap/pcapng capture that declares link-layer type 276 but the tool does not recognize or support it. Link-layer type 276 is an identifier for a specific data-link encapsulation; if the tool lacks a decoder for that DLT/LinkType, it reports “unknown or unsupported”. A pentester used a Nordic nRF52840 Dongle to
Your packets are there. You just need to teach your tool how to greet them.
In a hex editor, if you see 14 01 00 00 (little-endian for 0x0114 , which equals decimal 276), changing those bytes to 01 00 00 00 will instantly reconfigure the file to Link-Type 1 (Ethernet). Conclusion
: The version of Wireshark in the default repositories (like Ubuntu 20.04) is often too old. You can get the latest stable version by adding the Wireshark Dev PPA tcprewrite --dlt=enet --infile=input
: You captured data on a modern Linux distribution (such as Ubuntu 22.04+, Debian 12+, or Red Hat Enterprise Linux 9+) using a recent version of tcpdump or dumpcap on the any interface. These systems default to SLL2 (276) for pseudo-interfaces.
The fastest and cleanest solution is to update your packet capture tool to the latest stable release. Modern versions of Wireshark natively support LINKTYPE_SOME_IP (276).