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Port 5053 (rlm, rlm-disc)

IANA assigns port 5053 to rlm, rlm-disc: RLM License Server.

Registered (user) port, 1024-49151 TCPUDP

IANA assignment

Service nameProtoDescriptionAssigneeReference
rlm TCP RLM License Server Matt Christiano 2 -
rlm-disc UDP RLM Discovery Server Reprise Software Inc -

Registry dates for this port: registered 2008-07-28.

Check what is listening on port 5053

Linux: is anything listening on TCP 5053?
sudo ss -tlnp 'sport = :5053'
Linux: UDP 5053
sudo ss -ulnp 'sport = :5053'
Linux / macOS: which process owns the port
sudo lsof -nP -i :5053
Older Linux / BSD (net-tools)
sudo netstat -tlnp | grep ':5053 '
Windows (Command Prompt)
netstat -ano | findstr :5053
Windows (PowerShell)
Get-NetTCPConnection -LocalPort 5053 -State Listen | Select LocalAddress,OwningProcess

Test it from outside

From another machine
nc -vz -w 5 HOST 5053
From Windows
Test-NetConnection HOST -Port 5053
UDP probe (no reply does not prove it is closed)
nc -vzu -w 5 HOST 5053

Block port 5053 in the firewall

ufw
sudo ufw deny 5053/tcp
iptables
sudo iptables -A INPUT -p tcp --dport 5053 -j DROP
nftables
sudo nft add rule inet filter input tcp dport 5053 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block TCP 5053' -Direction Inbound -Protocol TCP -LocalPort 5053 -Action Block
ufw
sudo ufw deny 5053/udp
iptables
sudo iptables -A INPUT -p udp --dport 5053 -j DROP
nftables
sudo nft add rule inet filter input udp dport 5053 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block UDP 5053' -Direction Inbound -Protocol UDP -LocalPort 5053 -Action Block

Related ports

5051ita-agent5052ita-manager5054rlm-admin5055unot

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