Port 1193 belongs to the registered port range (1024-49151)—numbers that IANA assigns to specific applications and services upon request. Unlike well-known ports (0-1023), registered ports don't require special privileges to use, making them ideal for commercial software that needs a consistent port number across installations.
Port 1193 is officially assigned to the Five Across Server, a workgroup instant messaging and collaboration platform that existed briefly in the mid-2000s and then disappeared.12
What Five Across Was
Five Across launched in late 2003 with InterComm, an instant messaging client that ran on its own proprietary network. At the time, enterprises were struggling with employees using consumer IM platforms (AIM, MSN Messenger, Yahoo) that IT departments couldn't control or monitor.2
Five Across offered a solution: bring instant messaging behind the firewall. The Five Across Workgroup Server let companies run their own IM infrastructure with features that mattered to IT—logging, auditing, access control, and the ability to keep all chat traffic inside the corporate network.2
The platform also included features designed for workgroup collaboration: organizing buddy lists by teams, storing shared documents in a server-based repository, and integrating RSS feeds into the IM client.2
Glenn Reid, the founder, registered port 1193 with IANA in November 2004 for both TCP and UDP.1 The registration gave Five Across Server a permanent address in the Internet's namespace—a stake in the ground that said "this protocol exists and this is where you'll find it."
What Happened
Cisco acquired Five Across in 2007.3 Like many acquisitions, the product was absorbed into Cisco's larger unified communications portfolio and eventually discontinued. The technology may have influenced Cisco's later collaboration tools, but the Five Across brand and protocol disappeared.
Port 1193 remained registered. Once IANA assigns a port number, it generally stays assigned even if the service stops existing. The registry is permanent. The services are not.
What This Port Teaches Us
Port 1193 is a ghost. It has an official assignment, a description in the IANA registry, and virtually no traffic. If you scan for it on the Internet today, you'll find almost nothing listening.
There are thousands of ports like this in the registered range—addresses reserved for products that had their moment, got acquired, got shut down, or simply failed to gain traction. Each one represents someone's attempt to build something that would last. Most didn't.
The registered port range (1024-49151) contains over 48,000 possible addresses. IANA has assigned thousands of them. But only a fraction carry meaningful traffic. The rest are artifacts—breadcrumbs left by software that came and went.
Port 1193 was supposed to carry the future of enterprise instant messaging. Now it carries almost nothing. But the reservation remains, a memorial in a registry that never forgets.
How to Check What's Listening
Even though port 1193 is unlikely to be in use, you can check what's listening on your system:
On Linux or macOS:
On Windows:
If something is listening on port 1193, it's almost certainly not Five Across. It could be:
- A different application repurposing the port number
- A test service or development server
- Malware using an obscure port to avoid detection
The port number is just an address. What listens there can be anything.
Why Registered Ports Matter
The registered port range exists to give applications consistent, non-conflicting addresses. When you install software that needs to listen on a network port, the developers have three options:
- Use a well-known port (0-1023) — Requires root/admin privileges, reserved for system services
- Register a port with IANA (1024-49151) — Guarantees no conflicts with other registered services
- Use a dynamic/ephemeral port (49152-65535) — No conflicts, but no consistency across installations
Five Across chose option two. They wanted port 1193 to mean "Five Across Server" everywhere their software was installed. IANA granted the request. The protocol died. The port number remains.
That's how the system works. Port numbers outlive the protocols they were built for. The Internet never forgets the addresses—only what used to live there.
Related Ports
- Port 1194 — OpenVPN (still very much alive, carrying millions of VPN connections)
- Port 5222 — XMPP/Jabber client connections (another enterprise messaging protocol, this one survived)
- Port 5269 — XMPP server-to-server connections
Frequently Asked Questions About Port 1193
Trang này có hữu ích không?