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Registered port (1024–10000) Standard/Low risk

Port 7701 NFAPI

Quick answer

Port 7701 is the IANA-assigned nfapi port for SCF nFAPI defining MAC/PHY split (SCTP).

Check and block Is it safe? Troubleshooting FAQ
TransportSCTP
RiskStandard/Low
Typical useApplication services

What is port 7701 used for?

Port 7701 is assigned to nfapi and uses SCTP. The IANA registry describes the service as “SCF nFAPI defining MAC/PHY split”. It sits in the registered range, the block used by databases, application servers and developer tooling. Port conflicts here are common when several local services start at once.

Ports are the transport-layer address a service listens on. This entry has no TCP assignment; SCTP clients establish their own association and fail in protocol-specific ways. That is why a port conflict appears whenever two processes try to bind the same number.

Use the commands below to confirm whether port 7701 is actually in use before you change firewall rules. Blocking the port stops new inbound traffic at the firewall, but it does not stop a local process from listening, and it does not remove the service from the machine.

Source: IANA Service Name and Transport Protocol Port Number Registry. Registered assignee: [Small_Cell_Forum].

Check and block port 7701

Copy-ready commands for the protocols assigned to this port. Run the check first, then block only what should not be reachable.

Check on Linux

sudo ss -Slpn 'sport = :7701'

Check on Windows

# No built-in Windows cmdlet for SCTP endpoints; use the vendor's diagnostic tool.

Block with UFW

# UFW does not manage SCTP rules; use iptables or nftables.

Block with iptables

sudo iptables -A INPUT -p sctp --dport 7701 -j DROP

These commands are examples for a typical host. Check the listener before you change firewall rules, and persist iptables rules with iptables-save or netfilter-persistent. On Windows, use Windows Defender Firewall or New-NetFirewallRule for persistent blocks. The iptables rules here cover IPv4; mirror them with ip6tables if IPv6 is enabled. UFW and the built-in Windows cmdlets cover TCP and UDP only; this port also lists SCTP, so use nftables, iptables or the vendor's diagnostic tool for those protocols. SCTP and DCCP handling also depends on kernel support, including their diagnostic modules, so a missing result may mean the module is not loaded rather than that nothing is listening.

Is port 7701 safe to expose?

Standard/Low

This port is not on our curated list of services with a widely exploited profile. Exposure is only safe when the listening service is intended, patched and protected by a firewall. Keep the listening service patched and remove it if unused. A default-deny firewall policy with explicit allow rules is still the safest baseline.

Where port 7701 is usually used

Most traffic on port 7701 falls into these scenarios. The demo below is a safe way to confirm the listener before you change anything.

Demo

Confirm the SCTP listener

This port is not registered for TCP, so an nc TCP probe cannot confirm it. Run this on the host that runs the service; empty output means nothing is bound to port 7701.

sudo ss -Slpn 'sport = :7701'

Common problems with port 7701

No reply from the service

Because UDP has no handshake, a missing reply can mean the service is idle, the packet was dropped, or the client sent it to the wrong interface. Check the listener locally before blaming the network.

Port already in use

Find the process holding the port with sudo ss -ulpn 'sport = :7701' or sudo lsof -i :7701. Stop that process or configure it to bind another port; killing it without identifying it can take down a production service.

Firewall rule did not survive a reboot

UFW and Windows Firewall keep rules across restarts. Raw iptables rules do not: save them with iptables-save or the netfilter-persistent package, and re-apply after upgrades that reset the ruleset.

The port is blocked but still reachable

A firewall rule filters inbound traffic; it does not close the listener. Confirm with the check command above and bind the service to 127.0.0.1 when only local clients need it.

Port 7701 at a glance

Port number7701
Service namenfapi
Transport protocolSCTP
CategoryApplication services
RangeRegistered port (1024–10000)
Risk levelStandard/Low
Registered assignee[Small_Cell_Forum]
Registry descriptionSCF nFAPI defining MAC/PHY split
SourceIANA Service Name and Transport Protocol Port Number Registry

Frequently asked questions

What is port 7701 used for?

Port 7701 (NFAPI) uses SCTP. SCF nFAPI defining MAC/PHY split.

How do I check if port 7701 is open?

On Linux run `sudo ss -Slpn 'sport = :7701'`. On Windows run `# No built-in Windows cmdlet for SCTP endpoints; use the vendor's diagnostic tool.` in PowerShell. If the port is open, the output shows a process listening on port 7701; empty output usually means nothing is bound to it. UFW and the built-in Windows cmdlets cover TCP and UDP only; SCTP needs nftables, iptables or the vendor's diagnostic tool.

How do I block port 7701?

With iptables run `sudo iptables -A INPUT -p sctp --dport 7701 -j DROP`. Persist the iptables rules with your distribution's netfilter-persistent or iptables-save tooling so they survive a reboot. UFW covers TCP and UDP only; use iptables or nftables for SCTP.

Is port 7701 safe to expose?

This port is not on our curated list of services with a widely exploited profile. Exposure is only safe when the listening service is intended, patched and protected by a firewall. Nevertheless, keep the listening service patched and remove it if unused. A default-deny firewall policy with explicit allow rules is still the safest baseline.

Primary data: IANA Service Name and Transport Protocol Port Number Registry.

Last reviewed 2026-10-30 · Methodology · About · Privacy