{
  "port": 5190,
  "protocol": "both",
  "service": "AOL / OSCAR (AIM, ICQ)",
  "oneLiner": "The AOL instant-messaging port — AIM and ICQ signed on here, and both services are now dead.",
  "whatItIs": "IANA registered 5190 to America Online, and it carried the OSCAR protocol used by AIM and ICQ clients to log in and exchange messages. AIM shut down in December 2017 and ICQ in June 2024, so the original services no longer answer. What remains are firewall rules, IDS signatures and old clients that still name the port, plus the occasional third-party OSCAR revival server.",
  "exposure": {
    "verdict": "careful",
    "note": "OSCAR authentication and messages were not encrypted in the classic clients. Nothing legitimate should be listening on 5190 today; investigate anything that is."
  },
  "checkCommand": "nc -vz TARGET 5190",
  "links": [
    {
      "title": "IANA port registry — 5190 (aol)",
      "url": "https://www.iana.org/assignments/service-names-port-numbers/service-names-port-numbers.xhtml?search=5190",
      "kind": "iana"
    }
  ]
}