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Port 640 (entrust-sps)

IANA assigns port 640 to entrust-sps.

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

IANA assignment

Service nameProtoDescriptionAssigneeReference
entrust-sps TCP entrust-sps Marek Buchler -
entrust-sps UDP entrust-sps Marek Buchler -

Check what is listening on port 640

Linux: is anything listening on TCP 640?
sudo ss -tlnp 'sport = :640'
Linux: UDP 640
sudo ss -ulnp 'sport = :640'
Linux / macOS: which process owns the port
sudo lsof -nP -i :640
Older Linux / BSD (net-tools)
sudo netstat -tlnp | grep ':640 '
Windows (Command Prompt)
netstat -ano | findstr :640
Windows (PowerShell)
Get-NetTCPConnection -LocalPort 640 -State Listen | Select LocalAddress,OwningProcess

Test it from outside

From another machine
nc -vz -w 5 HOST 640
From Windows
Test-NetConnection HOST -Port 640
UDP probe (no reply does not prove it is closed)
nc -vzu -w 5 HOST 640

Block port 640 in the firewall

ufw
sudo ufw deny 640/tcp
iptables
sudo iptables -A INPUT -p tcp --dport 640 -j DROP
nftables
sudo nft add rule inet filter input tcp dport 640 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block TCP 640' -Direction Inbound -Protocol TCP -LocalPort 640 -Action Block
ufw
sudo ufw deny 640/udp
iptables
sudo iptables -A INPUT -p udp --dport 640 -j DROP
nftables
sudo nft add rule inet filter input udp dport 640 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block UDP 640' -Direction Inbound -Protocol UDP -LocalPort 640 -Action Block

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638mcns-sec639msdp641repcmd642esro-emsdp

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