Port 1311: RxMon — The Port That Dell Borrowed

Port 1311 sits in the registered port range (1024-49151) with an official IANA assignment to a service called "RxMon."¹ But here's the thing: nobody remembers what RxMon was supposed to do. The service name appears in the official registry, but the protocol itself has faded into obscurity.

What hasn't faded is what actually runs on port 1311 in the real world.

The Dell Connection

Port 1311 is famous for one thing: Dell OpenManage Server Administrator (OMSA).² This is Dell's web-based hardware management interface that lets administrators monitor server health, check RAID status, update firmware, and manage Dell hardware without physically touching the machine.

When you access https://hostname:1311/, you're connecting to the OMSA web console served by the DSM SA Connection Service. It's HTTPS-encrypted server management in a browser.³

For system administrators managing Dell infrastructure, port 1311 is instantly recognizable. This isn't an obscure protocol—it's part of the daily workflow for anyone responsible for Dell servers.

The Identity Split

Port 1311 has two identities:

Official: RxMon (TCP/UDP)—a service with no known implementation or documentation Actual: Dell OpenManage HTTPS—actively used on thousands of servers worldwide

This split between official assignment and real-world usage happens occasionally in the port number system. A company registers a port for internal use or builds a popular application before standardization matters, and the unofficial use becomes more widely known than whatever IANA originally registered.

Security Considerations

Because OMSA on port 1311 provides hardware-level access to servers, it's a target. Attackers scan for exposed management interfaces, and older OMSA versions have had vulnerabilities—everything from authentication bypasses to default credentials.⁴

Security recommendations:

• Restrict port 1311 to trusted management networks only
• Never expose it directly to the Internet
• Keep OMSA updated to patch known vulnerabilities
• Use strong authentication (disable default accounts)
• Consider certificate-based authentication for sensitive environments

Finding port 1311 open on a public-facing server is a red flag. Management interfaces belong behind firewalls.

Checking What's Listening

To see if something is listening on port 1311:

Linux/Mac:

sudo lsof -i :1311
netstat -an | grep 1311

Windows:

netstat -ano | findstr :1311
Get-NetTCPConnection -LocalPort 1311

If you see a process called dsm_om_connsvc or something related to Dell OpenManage, you've found the OMSA web server.

Why This Port Matters

Port 1311 illustrates something important about how port numbers actually work in practice. The IANA registry is authoritative, but it's not always reality. Ports get registered for services that never materialize. Popular applications claim ports before standardization. Real-world usage diverges from official assignments.

The registered port range (1024-49151) was created so organizations could register ports for their services without conflicts. RxMon registered 1311, but Dell's actual implementation of server management became what people associate with this number.

In the end, ports are just numbers. What matters is what's actually listening—and on port 1311, that's almost always Dell talking to administrators about hardware that needs attention.

Related Ports

• Port 1310 — Husky (another obscure IANA registration)
• Port 1312 — STM Studio (rarely encountered)
• Ports 443/8443 — Standard HTTPS ports that OMSA can also be configured to use