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Port 6241 (jeol-nsdtp-1, jeol-nsddp-1)

IANA assigns port 6241 to jeol-nsdtp-1, jeol-nsddp-1: JEOL Network Services Data Transport Protocol 1.

Registered (user) port, 1024-49151 TCPUDP

IANA assignment

Service nameProtoDescriptionAssigneeReference
jeol-nsdtp-1 TCP JEOL Network Services Data Transport Protocol 1 Kevin Wellwood -
jeol-nsddp-1 UDP JEOL Network Services Dynamic Discovery Protocol 1 Kevin Wellwood -

Registry dates for this port: registered 2008-04-17.

Check what is listening on port 6241

Linux: is anything listening on TCP 6241?
sudo ss -tlnp 'sport = :6241'
Linux: UDP 6241
sudo ss -ulnp 'sport = :6241'
Linux / macOS: which process owns the port
sudo lsof -nP -i :6241
Older Linux / BSD (net-tools)
sudo netstat -tlnp | grep ':6241 '
Windows (Command Prompt)
netstat -ano | findstr :6241
Windows (PowerShell)
Get-NetTCPConnection -LocalPort 6241 -State Listen | Select LocalAddress,OwningProcess

Test it from outside

From another machine
nc -vz -w 5 HOST 6241
From Windows
Test-NetConnection HOST -Port 6241
UDP probe (no reply does not prove it is closed)
nc -vzu -w 5 HOST 6241

Block port 6241 in the firewall

ufw
sudo ufw deny 6241/tcp
iptables
sudo iptables -A INPUT -p tcp --dport 6241 -j DROP
nftables
sudo nft add rule inet filter input tcp dport 6241 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block TCP 6241' -Direction Inbound -Protocol TCP -LocalPort 6241 -Action Block
ufw
sudo ufw deny 6241/udp
iptables
sudo iptables -A INPUT -p udp --dport 6241 -j DROP
nftables
sudo nft add rule inet filter input udp dport 6241 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block UDP 6241' -Direction Inbound -Protocol UDP -LocalPort 6241 -Action Block

Related ports

6209qmtps6222radmind6242jeol-nsdtp-2, jeol-nsddp-26243jeol-nsdtp-3, jeol-nsddp-3

All port numbers · Open port checker
Assignment data: IANA port number registry (public domain), retrieved 2026-11-10.