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Port 642 (esro-emsdp)

IANA assigns port 642 to esro-emsdp: ESRO-EMSDP V1.3.

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

IANA assignment

Service nameProtoDescriptionAssigneeReference
esro-emsdp TCP ESRO-EMSDP V1.3 Mohsen Banan 2 -
esro-emsdp UDP ESRO-EMSDP V1.3 Mohsen Banan 2 -

Check what is listening on port 642

Linux: is anything listening on TCP 642?
sudo ss -tlnp 'sport = :642'
Linux: UDP 642
sudo ss -ulnp 'sport = :642'
Linux / macOS: which process owns the port
sudo lsof -nP -i :642
Older Linux / BSD (net-tools)
sudo netstat -tlnp | grep ':642 '
Windows (Command Prompt)
netstat -ano | findstr :642
Windows (PowerShell)
Get-NetTCPConnection -LocalPort 642 -State Listen | Select LocalAddress,OwningProcess

Test it from outside

From another machine
nc -vz -w 5 HOST 642
From Windows
Test-NetConnection HOST -Port 642
UDP probe (no reply does not prove it is closed)
nc -vzu -w 5 HOST 642

Block port 642 in the firewall

ufw
sudo ufw deny 642/tcp
iptables
sudo iptables -A INPUT -p tcp --dport 642 -j DROP
nftables
sudo nft add rule inet filter input tcp dport 642 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block TCP 642' -Direction Inbound -Protocol TCP -LocalPort 642 -Action Block
ufw
sudo ufw deny 642/udp
iptables
sudo iptables -A INPUT -p udp --dport 642 -j DROP
nftables
sudo nft add rule inet filter input udp dport 642 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block UDP 642' -Direction Inbound -Protocol UDP -LocalPort 642 -Action Block

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