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Port 597 (ptcnameservice)

IANA assigns port 597 to ptcnameservice: PTC Name Service.

Well-known (system) port, 0-1023 TCPUDP

IANA assignment

Service nameProtoDescriptionAssigneeReference
ptcnameservice TCP PTC Name Service Yuri Machkasov -
ptcnameservice UDP PTC Name Service Yuri Machkasov -

Check what is listening on port 597

Linux: is anything listening on TCP 597?
sudo ss -tlnp 'sport = :597'
Linux: UDP 597
sudo ss -ulnp 'sport = :597'
Linux / macOS: which process owns the port
sudo lsof -nP -i :597
Older Linux / BSD (net-tools)
sudo netstat -tlnp | grep ':597 '
Windows (Command Prompt)
netstat -ano | findstr :597
Windows (PowerShell)
Get-NetTCPConnection -LocalPort 597 -State Listen | Select LocalAddress,OwningProcess

Test it from outside

From another machine
nc -vz -w 5 HOST 597
From Windows
Test-NetConnection HOST -Port 597
UDP probe (no reply does not prove it is closed)
nc -vzu -w 5 HOST 597

Block port 597 in the firewall

ufw
sudo ufw deny 597/tcp
iptables
sudo iptables -A INPUT -p tcp --dport 597 -j DROP
nftables
sudo nft add rule inet filter input tcp dport 597 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block TCP 597' -Direction Inbound -Protocol TCP -LocalPort 597 -Action Block
ufw
sudo ufw deny 597/udp
iptables
sudo iptables -A INPUT -p udp --dport 597 -j DROP
nftables
sudo nft add rule inet filter input udp dport 597 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block UDP 597' -Direction Inbound -Protocol UDP -LocalPort 597 -Action Block

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