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Port 18241 (checkpoint-rtm)

IANA assigns port 18241 to checkpoint-rtm: Check Point RTM.

Registered (user) port, 1024-49151 TCPUDP

IANA assignment

Service nameProtoDescriptionAssigneeReference
checkpoint-rtm TCP Check Point RTM Dudi Hazan -
checkpoint-rtm UDP Check Point RTM Dudi Hazan -

Check what is listening on port 18241

Linux: is anything listening on TCP 18241?
sudo ss -tlnp 'sport = :18241'
Linux: UDP 18241
sudo ss -ulnp 'sport = :18241'
Linux / macOS: which process owns the port
sudo lsof -nP -i :18241
Older Linux / BSD (net-tools)
sudo netstat -tlnp | grep ':18241 '
Windows (Command Prompt)
netstat -ano | findstr :18241
Windows (PowerShell)
Get-NetTCPConnection -LocalPort 18241 -State Listen | Select LocalAddress,OwningProcess

Test it from outside

From another machine
nc -vz -w 5 HOST 18241
From Windows
Test-NetConnection HOST -Port 18241
UDP probe (no reply does not prove it is closed)
nc -vzu -w 5 HOST 18241

Block port 18241 in the firewall

ufw
sudo ufw deny 18241/tcp
iptables
sudo iptables -A INPUT -p tcp --dport 18241 -j DROP
nftables
sudo nft add rule inet filter input tcp dport 18241 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block TCP 18241' -Direction Inbound -Protocol TCP -LocalPort 18241 -Action Block
ufw
sudo ufw deny 18241/udp
iptables
sudo iptables -A INPUT -p udp --dport 18241 -j DROP
nftables
sudo nft add rule inet filter input udp dport 18241 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block UDP 18241' -Direction Inbound -Protocol UDP -LocalPort 18241 -Action Block

Related ports

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