The TLS-wrapped half of the CAC App Service Protocol registration; the cleartext side sits on 1130.
IANA registered 1131 in February 2006 as caspssl, "CAC App Service Protocol Encripted" (the misspelling is in the registry), paired with casp on 1130 for the unencrypted form. No public specification accompanies the registration, and Nmap's frequency data shows it open on almost no hosts. If 1131 is listening, identify the application; the registry name only tells you the vendor intended TLS.
Expose with care
The registration implies TLS, but that guarantees nothing about the process actually bound here — verify with a handshake before treating it as encrypted.
$ openssl s_client -connect TARGET:1131 -servername TARGETSeen this on your network? Beige Box scans your Wi-Fi and shows every open port on every device — and its Ports tool links straight back here.
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