Port 457: SCOhelp — The Unix Help System Time Forgot

What Port 457 Is

Port 457 is officially assigned to scohelp, an HTTP documentation server that ran on SCO UnixWare systems.¹ The service was registered with IANA under the name "scohelp" for both TCP and UDP protocols.

This is a well-known port (in the 0-1023 range), which means it requires root privileges to bind on Unix-like systems. That designation made sense in the 1990s when SCO UnixWare was a commercial Unix contender. It makes less sense now that SCO UnixWare has faded into history.

The Story: When Unix Had Built-In Web Servers for Help Files

In the mid-1990s, as the web was becoming ubiquitous, every Unix vendor had the same idea: why not serve system documentation over HTTP? Users already had browsers. HTTP was the future. It seemed obvious.

SCO UnixWare 7 shipped with scohelp, a lightweight HTTP server that listened on port 457 and served manual pages, system documentation, and help files.² You didn't need to remember man command syntax or navigate text interfaces. Just point your browser at http://localhost:457 and browse the docs like a website.

For a moment, this felt innovative. Then the web kept evolving, documentation moved online, and embedding HTTP servers in operating systems started feeling weird. By UnixWare 7.1.4, SCO had replaced scohelp with DocView, which ran on port 8458.³ The new system coexisted with the old one on upgraded systems, but fresh installations dropped scohelp entirely.

Port 457 became a ghost. The service it was assigned to barely exists anymore. SCO itself went through bankruptcy, litigation, and rebrand after rebrand. What remains is an officially assigned port that almost nothing uses.

How It Worked

Scohelp was a simple HTTP server. It didn't handle dynamic content or user authentication. It just served static documentation files—man pages, installation guides, system administration docs—formatted as HTML.⁴

The service started automatically on UnixWare systems through scripts in /etc/rc2.d. If you needed to access documentation, you opened a browser and navigated to the system's hostname or IP address on port 457. The server would present a directory-style interface where you could browse through categories of help files.

It was functional. It was also completely unnecessary once the web became the primary documentation platform. Why serve docs locally when you can host them centrally and update them without patching every installation?

Security Considerations

Port 457 has been associated with malware in the past.⁵ A Trojan or virus used this port for communication, likely because it was assigned but rarely monitored. An obscure port with an official assignment is perfect for hiding malicious traffic—it looks legitimate enough to slip past casual inspection.

If you see traffic on port 457 today, investigate it. The odds that you're running SCO UnixWare with scohelp active are low. The odds that something else is using the port are higher.

Check what's listening:

# On Linux/Unix
sudo lsof -i :457
sudo netstat -tulpn | grep :457

# On Windows
netstat -ano | findstr :457

If something is bound to port 457 and it's not a legacy UnixWare system, find out what it is and why.

Why Assigned Ports Matter

Port 457 is a reminder that the port number space is not infinite and assignments are not always permanent in practice. IANA assigns ports based on applications that exist at a moment in time. Some of those applications become foundational (SSH on 22, HTTPS on 443). Others fade away, leaving their port numbers as historical markers.

The well-known port range (0-1023) was supposed to be reserved for essential services. But "essential" changes. What mattered in 1995 doesn't necessarily matter in 2026. Port 457 is officially assigned, but functionally abandoned.

This creates a strange kind of technical debt. The port is taken, so nothing else can officially use it. But the service it was assigned to barely exists, so the reservation feels wasteful. IANA doesn't typically reclaim ports, so 457 remains assigned to scohelp indefinitely, a monument to a help system that history outgrew.

Related Ports

• Port 8458 — DocView, the successor to scohelp on later UnixWare systems³
• Port 80 — HTTP, the protocol scohelp used for serving documentation
• Port 443 — HTTPS, where modern documentation lives