# Libpcap File Format (nanosecond-resolution) — file signature 4D 3C B2 A1 (little-endian) at offset 0 For Libpcap File Format (nanosecond-resolution), hex signature is 4D 3C B2 A1 (little-endian); offset is 0; extension is pcap, verified against its source on 2026-09-22. - **Hex signature:** 4D 3C B2 A1 (little-endian) _(verified: appears in the quote below)_ - **Offset:** 0 _(verified: appears in the quote below)_ - **Extension:** pcap _(verified: appears in the quote below)_ - **Format:** Libpcap File Format (nanosecond-resolution) _(verified: appears in the quote below)_ ## What the source says > 4D 3C B2 A1 (little-endian) | M<²¡ | 0 | pcap | Libpcap File Format (nanosecond-resolution) [2] | ## Source - https://en.wikipedia.org/wiki/List_of_file_signatures Last verified: 2026-09-22. Review by: 2027-09-22. Part of [File format magic numbers](https://referencesource.org/file-format-signatures/).