PortAtlas.
Registered port (1024–10000) Standard/Low risk

Port 6241 JEOL-NSDDP-1

Quick answer

Port 6241 has a different IANA assignment for each transport protocol: TCP jeol-nsdtp-1; UDP jeol-nsddp-1.

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

What is port 6241 used for?

Port 6241 carries a different IANA service on each transport protocol: TCP jeol-nsdtp-1; UDP jeol-nsddp-1. 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. The same port is also registered under jeol-nsdtp-1.

Each transport reaches a different service on this number, so match the protocol to the service you are diagnosing. A TCP check says nothing about a UDP listener on the same port, and the reverse is also true. Both transports still bind to the same number, which is why two processes can collide even when they use different protocols.

Use the commands below to confirm whether port 6241 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: [Kevin_Wellwood].

Check and block port 6241

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 -tlpn 'sport = :6241' sudo ss -ulpn 'sport = :6241'

Check on Windows

Get-NetTCPConnection -LocalPort 6241 -State Listen -ErrorAction SilentlyContinue Get-NetUDPEndpoint -LocalPort 6241 -ErrorAction SilentlyContinue

Block with UFW

sudo ufw deny 6241/tcp sudo ufw deny 6241/udp

Block with iptables

sudo iptables -A INPUT -p tcp --dport 6241 -j DROP sudo iptables -A INPUT -p udp --dport 6241 -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.

Is port 6241 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 6241 is usually used

Most traffic on port 6241 falls into these scenarios. The demo below is a safe way to confirm the listener before you change anything.

Demo

Probe the port

Confirm something is listening before you debug the client. This checks a TCP handshake on the port.

nc -vz 127.0.0.1 6241

Common problems with port 6241

Connection refused or timed out

Refused usually means the host is reachable but nothing is listening on port 6241. A timeout more often means a firewall drop, a wrong host or a service bound to a different interface.

Port already in use

Find the process holding the port with sudo ss -tlpn 'sport = :6241' or sudo lsof -i :6241. 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 6241 at a glance

Port number6241
Service namejeol-nsddp-1
Aliasesjeol-nsdtp-1
Transport protocolTCP / UDP
Assignments by protocol
  • TCP jeol-nsdtp-1 — JEOL Network Services Data Transport Protocol 1
  • UDP jeol-nsddp-1 — JEOL Network Services Dynamic Discovery Protocol 1
CategoryApplication services
RangeRegistered port (1024–10000)
Risk levelStandard/Low
Registered assignee[Kevin_Wellwood]
Registry descriptionJEOL Network Services Dynamic Discovery Protocol 1
SourceIANA Service Name and Transport Protocol Port Number Registry

Frequently asked questions

What is port 6241 used for?

Port 6241 (JEOL-NSDDP-1). The IANA registry assigns a different service on each transport protocol: TCP jeol-nsdtp-1; UDP jeol-nsddp-1.

How do I check if port 6241 is open?

On Linux run `sudo ss -tlpn 'sport = :6241'` and `sudo ss -ulpn 'sport = :6241'`. On Windows run `Get-NetTCPConnection -LocalPort 6241 -State Listen -ErrorAction SilentlyContinue` and `Get-NetUDPEndpoint -LocalPort 6241 -ErrorAction SilentlyContinue` in PowerShell. If the port is open, the output shows a process listening on port 6241; empty output usually means nothing is bound to it.

How do I block port 6241?

With UFW run `sudo ufw deny 6241/tcp` and `sudo ufw deny 6241/udp`. With iptables run `sudo iptables -A INPUT -p tcp --dport 6241 -j DROP` and `sudo iptables -A INPUT -p udp --dport 6241 -j DROP`. Persist the iptables rules with your distribution's netfilter-persistent or iptables-save tooling so they survive a reboot.

Is port 6241 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