Port 9510 – Unassigned High Port (Fingerprint-First, Not NCSA Telnet)

Port 9510 has no service registered with IANA — it sits in the user-ports range (1024–49151) but the registry assigns it no name, so there is no “standard” thing that runs here. The old “ncsa-telnet” label attached to this port is a mislabel: NCSA Telnet was a 1990s Telnet client from the National Center for Supercomputing Applications, and Telnet’s actual port is 23, not 9510. In practice a listener on 9510 is whatever an application happened to bind there — one well-documented example is IBM Flex System Manager’s Common Agent Services (CAS) Agent Manager — so the entire job on an open 9510 is to fingerprint what is actually answering, not to attack an assumed protocol.

Why It’s Open

Because 9510 is unregistered, anything can claim it, and what you find is site-specific rather than a known daemon:

• Vendor management agents. The best-documented real use is IBM Flex System Manager (FSM): its Common Agent Services (CAS) endpoints talk to the Agent Manager over TCP 9510. On IBM systems-management estates this is the most likely occupant.
• Custom and internal applications. When the obvious ports are taken, developers reach for memorable high numbers like 9510 for internal APIs, admin consoles, or app back-ends. These are frequently undocumented and unauthenticated.
• A mislabeled or legacy telnet-style interface. Some appliances expose a cleartext, Telnet-like admin shell on a non-standard high port. If that is what answers here, treat it exactly like Telnet on port 23 — every keystroke and credential is on the wire.

If you are cataloguing neighbouring high ports, the sibling pages for port 9512 and port 9999 follow the same “identify before you trust it” logic.

Common Risks

• Unknown service, unknown attack surface. With no registered protocol, an open 9510 could be a management agent, a web API, or a cleartext admin shell — dismissing it as “just NCSA Telnet” hides whatever is really there.
• Weak or anonymous TLS. The IBM FSM/CAS listener on 9510 was designed to negotiate anonymous ciphers (aNULL) — encryption with no server authentication, which is trivially machine-in-the-middled. Security scanners flag this specifically, and any home-grown TLS on 9510 tends to be just as weak.
• Cleartext credential exposure. If the service is a Telnet-style or plain-HTTP admin interface, credentials and commands travel unencrypted and can be sniffed off the path.
• Unauthenticated internal apps. Custom back-ends bound to a high port are often shipped with no auth, verbose errors, or debug endpoints exposed.
• Information disclosure via banners. Version strings, product names, and stack traces on 9510 hand an attacker exactly the fingerprint they need to pick the right exploit.

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Enumeration & Testing

There is no “port 9510 protocol” to attack, so the whole game is identification. Version-scan it, see whether it speaks HTTP or TLS, and only then decide how to test it.

Detect the service and version (TCP and UDP)

nmap -sV --version-intensity 9 -p 9510 <target>
nmap -sU -sV -p 9510 <target>

Grab the raw banner

nc -nv <target> 9510
nmap --script banner -p 9510 <target>

Check whether it answers as HTTP

curl -sI http://<target>:9510/
curl -skI https://<target>:9510/

A Server: or X-Powered-By header tells you it is a web app — read the headers to fingerprint the stack, then test it like any other web service.

Inspect the TLS layer (catch the anonymous-cipher weakness)

nmap --script ssl-enum-ciphers -p 9510 <target>
openssl s_client -connect <target>:9510

ssl-enum-ciphers will list any anonymous (aNULL / ADH) or otherwise weak ciphers — the exact issue documented on IBM’s CAS listener.

If it looks like a Telnet-style shell

telnet <target> 9510

Log the confirmed service, version, and any weak-cipher or cleartext finding as you go, so the evidence lands in the pentest report instead of a scratch terminal you’ll lose.

What to Look For

Known CVEs and Exploits

There is no CVE tied to port 9510 itself, because the port carries no standard service — the risks here are design-level (weak/anonymous TLS, cleartext admin interfaces, unauthenticated custom apps), not a single named network bug. Any CVE that actually matters belongs to whatever product you positively fingerprint on the port; identify it first, then check that vendor’s advisories.

The previous version of this page listed three CVEs, all of which were wrong for this port and have been removed:

• CVE-2005-0468 was described as a “FirstClass Internet Services buffer overflow.” It is actually a heap overflow in env_opt_add in the BSD Telnet client (telnet.c) — a client-side bug, not a FirstClass flaw and not a service on port 9510.
• CVE-1999-0621 was cited as an “NCSA Telnet cleartext credentials” issue. On NVD it is a REJECTED entry whose original text was merely “a component service related to NETBIOS is running” — not a vulnerability at all.
• CVE-1999-0504 was labelled “default password in educational software.” It actually describes a Windows NT account with a null, blank, or default password — a configuration-audit item for Windows, unrelated to port 9510.

Always verify a CVE against its NVD record and confirm the product and version match the service you actually found before trusting it.

Mitigation

• Identify the service, then harden that. You cannot secure “port 9510” generically — fingerprint the real occupant and apply that product’s guidance.
• Kill anonymous and weak ciphers. If TLS on 9510 offers aNULL/ADH ciphers (as older IBM FSM/CAS builds did), reconfigure it to require authenticated, modern cipher suites and re-scan with ssl-enum-ciphers to confirm.
• Replace any cleartext admin interface. If it turns out to be a Telnet-style shell, retire it in favour of an encrypted, authenticated channel — the same argument that applies to Telnet on port 23.
• Authenticate custom apps. Put internal/dev services behind real authentication and TLS, and disable debug and verbose-error output on anything reachable off-host.
• Firewall it to who needs it. Restrict TCP 9510 to the specific management hosts or clients that require it, and audit cloud security groups and container port maps for an accidental 0.0.0.0:9510.
• Close it if nothing owns it. An unexplained listener on an unregistered port is worth chasing down; stop the service and rescan to confirm the port is closed.

Real-World Example

The most concrete thing ever documented on port 9510 is not an exploit but a design weakness. IBM Flex System Manager’s Common Agent Services listen on TCP 9510 for the Agent Manager, and that channel was originally built to negotiate anonymous TLS ciphers — encryption with no certificate check on either end. Security scanners routinely flagged 9510 for “supporting anonymous ciphers” (IBM tracked and eventually fixed it under APAR IC94175), because an anonymous cipher gives an on-path attacker a clean machine-in-the-middle: the traffic looks encrypted but nothing proves you are talking to the real Agent Manager. It is the port-9510 lesson in miniature — the port number tells you nothing, but the actual service behind it (here, a management agent with weak TLS) is the real attack surface, and you only find it by fingerprinting.

FAQ

What is port 9510 used for?

Port 9510 has no IANA-registered service — the registry assigns it no standard protocol. Whatever runs there is application-specific. A well-documented real example is IBM Flex System Manager’s Common Agent Services (CAS) talking to its Agent Manager, but it can equally be a custom internal app or, occasionally, a mislabeled Telnet-style admin interface. Fingerprint it to know for sure.

Is port 9510 the NCSA Telnet port?

No. That label is a mislabel. NCSA Telnet was a 1990s Telnet client from the National Center for Supercomputing Applications, and the Telnet protocol runs on port 23, not 9510. There is no registered “ncsa-telnet” service on 9510.

Is port 9510 dangerous?

The port number is neutral; the risk depends on what is listening. The documented concerns are design-level: TLS with anonymous ciphers (no server authentication), cleartext admin interfaces, and unauthenticated custom apps. Identify the service and assess that — do not assume an open 9510 is harmless just because it has no famous CVE.

Does port 9510 have any known CVEs?

None that belong to the port itself. The three CVEs an older version of this page listed were all wrong-service or rejected entries and have been removed. Any real CVE applies to the specific product you fingerprint on the port, so check that vendor’s advisories once you know what it is.

How do I find out what is running on my port 9510?

Fingerprint it: nmap -sV -p 9510 <host> for the service and version, nc -nv <host> 9510 for a raw banner, curl -skI https://<host>:9510/ to see whether it speaks HTTP/TLS, and nmap --script ssl-enum-ciphers -p 9510 <host> to check the cipher suite. A named product, a Server: header, a weak-cipher list, or a cleartext prompt each tell you how to proceed.

TL;DR

• Service: none registered with IANA — fingerprint the real occupant (documented example: IBM Flex System Manager Common Agent Services); not NCSA Telnet, which is a client and uses port 23
• Default port: 9510/TCP (unassigned in the IANA registry)
• Biggest risk: an unidentified service assumed to be benign — in practice weak/anonymous TLS, a cleartext admin interface, or an unauthenticated custom app
• Mitigation: identify the service, kill anonymous/weak ciphers, replace cleartext admin channels, authenticate custom apps, and firewall or close 9510 if nothing owns it