Port 3420: iFCP — Fibre Channel's attempt to cross the IP bridge

What Runs on Port 3420

Port 3420 is assigned to iFCP — Internet Fibre Channel Protocol — a gateway-to-gateway protocol that carries Fibre Channel storage traffic over TCP/IP networks.¹

Fibre Channel is the high-speed fabric that connects servers to storage arrays in data centers. It's fast, reliable, and speaks its own language — a language that has nothing to do with IP. iFCP was the bridge: a way to take Fibre Channel frames and ship them inside TCP connections, so existing storage hardware could communicate across IP infrastructure without being replaced.

Port 3420 is where that bridge opens.

How iFCP Works

iFCP operates between gateways — devices that sit at the edge of a Fibre Channel fabric and handle the translation to and from IP. When a server sends a Fibre Channel frame destined for a storage target on the other side of an IP network, the local gateway encapsulates that frame in a TCP session on port 3420. The remote gateway unwraps it and delivers it to the destination storage device as if it had never left Fibre Channel territory.

The storage devices themselves don't know anything changed. They speak Fibre Channel. The gateways speak both.

A Protocol with a Complicated History

RFC 4172 was published in September 2005.² At the time, the storage industry was wrestling with a real tension: Fibre Channel was the performance king, but IP networks were everywhere and cheap. The question was how to bridge them.

iFCP was one answer. It defined two operating modes:

• Address Translation Mode — the gateway rewrites Fibre Channel addresses as traffic crosses the IP boundary
• Address Transparent Mode — the gateway passes Fibre Channel addresses through unchanged

By 2011, IETF published RFC 6172, deprecating the address translation mode.³ The reason was blunt: Fibre Channel control frame formats had changed significantly since 2005, making the translation logic incorrect. More damning, no one was using it anyway. Every real-world iFCP deployment had chosen transparent mode.

The translation mode was abandoned. Transparent mode survives — used specifically for Fibre Channel inter-switch links across IP networks.

Who Uses This Port Today

iFCP never became dominant. The storage industry largely moved toward iSCSI (port 3260) for IP-based storage, and later toward NVMe-over-Fabrics for high-performance use cases. iFCP occupies a narrow niche: enterprise environments with existing Fibre Channel investments that need to stretch across an IP WAN without replacing hardware.

If you see traffic on port 3420, you're almost certainly looking at a specialized storage network, not a general-purpose service.

Checking What's on This Port

To see if anything is listening on port 3420 on your system:

# Linux / macOS
ss -tlnp | grep 3420
lsof -i :3420

# Windows
netstat -ano | findstr :3420

On a typical workstation or server, nothing will be listening here. This port belongs to enterprise storage gear, not software you'd install from a package manager.