Internet-Security.com TCP port 548 details

TCP port 548 is used by Apple Filing Protocol (AFP) for network file sharing.
macOS and OS X Server historically provided AFP file sharing on 548 via the built-in File Sharing service.
Apple’s AirPort Time Capsule and older Time Machine network backups used AFP over 548.
Many NAS devices offered AFP on this port, including Synology DSM (AFP service), QNAP, and FreeNAS/TrueNAS via Netatalk.
On Linux and BSD, the Netatalk daemon (afpd) listens on 548 to serve AFP shares.
Apple has deprecated AFP in favor of SMB, but 548 remains in use on legacy Macs and some NAS appliances.
Security note: Internet-exposed AFP/548 has seen exploitation, including a 2022 Netatalk unauthenticated remote code execution flaw and brute-force attacks against NAS credentials.

TCP 548