A SQL Anywhere database engine — the embedded Sybase database inside a lot of shipped software.
SQL Anywhere's database server binds TCP 2638 by default and also listens on UDP 2638 so clients can find servers by broadcast, including on other subnets. If the port is taken the engine picks another, starting at 49152, so 2638 is the common but not guaranteed case. It usually appears not because someone chose Sybase but because a vendor embedded it — backup products, point-of-sale, MDM and monitoring suites all ship SQL Anywhere underneath.
Do not expose
A database engine reachable from the internet is a credential-guessing target, and the UDP side answers discovery probes that tell a scanner the server and database names.
$ nc -vz -w 3 TARGET 2638Seen 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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Corrections or a missing port? Reply @rimrocksystems.