Unassignable dynamic port; on a Windows scan it is almost always an RPC endpoint handed out by the endpoint mapper.
49158 sits inside 49152-65535, the Dynamic/Private range that RFC 6335 says cannot be assigned through IANA and must not be used as a service identifier. Windows Vista and Server 2008 moved the default dynamic client port range to 49152-65535 (KB 929851), so RPC-based Windows services grab numbers here at startup unless an administrator pins them. A scan showing 49158 open on a Windows host means some RPC interface is listening; which one is only answerable by asking the endpoint mapper on port 135, and the answer can change after a reboot.
Do not expose
Windows RPC endpoints in this range should not face the internet. Microsoft's port-requirements guidance expects 49152-65535 to be reachable only between servers inside a segmented network.
$ nmap -Pn -sV -p 135,49158 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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