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Port 5318 (pkix-cmc)

IANA assigns port 5318 to pkix-cmc: PKIX Certificate Management using CMS (CMC).

Registered (user) port, 1024-49151 TCP

IANA assignment

Service nameProtoDescriptionAssigneeReference
pkix-cmc TCP PKIX Certificate Management using CMS (CMC) IESG RFC 10003

Registry dates for this port: last modified 2026-02-13.

Check what is listening on port 5318

Linux: is anything listening on TCP 5318?
sudo ss -tlnp 'sport = :5318'
Linux / macOS: which process owns the port
sudo lsof -nP -i :5318
Older Linux / BSD (net-tools)
sudo netstat -tlnp | grep ':5318 '
Windows (Command Prompt)
netstat -ano | findstr :5318
Windows (PowerShell)
Get-NetTCPConnection -LocalPort 5318 -State Listen | Select LocalAddress,OwningProcess

Test it from outside

From another machine
nc -vz -w 5 HOST 5318
From Windows
Test-NetConnection HOST -Port 5318

Block port 5318 in the firewall

ufw
sudo ufw deny 5318/tcp
iptables
sudo iptables -A INPUT -p tcp --dport 5318 -j DROP
nftables
sudo nft add rule inet filter input tcp dport 5318 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block TCP 5318' -Direction Inbound -Protocol TCP -LocalPort 5318 -Action Block

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Assignment data: IANA port number registry (public domain), retrieved 2026-11-10.