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Port 477 (ss7ns)

IANA assigns port 477 to ss7ns.

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

IANA assignment

Service nameProtoDescriptionAssigneeReference
ss7ns TCP ss7ns Jean Michel URSCH -
ss7ns UDP ss7ns Jean Michel URSCH -

Check what is listening on port 477

Linux: is anything listening on TCP 477?
sudo ss -tlnp 'sport = :477'
Linux: UDP 477
sudo ss -ulnp 'sport = :477'
Linux / macOS: which process owns the port
sudo lsof -nP -i :477
Older Linux / BSD (net-tools)
sudo netstat -tlnp | grep ':477 '
Windows (Command Prompt)
netstat -ano | findstr :477
Windows (PowerShell)
Get-NetTCPConnection -LocalPort 477 -State Listen | Select LocalAddress,OwningProcess

Test it from outside

From another machine
nc -vz -w 5 HOST 477
From Windows
Test-NetConnection HOST -Port 477
UDP probe (no reply does not prove it is closed)
nc -vzu -w 5 HOST 477

Block port 477 in the firewall

ufw
sudo ufw deny 477/tcp
iptables
sudo iptables -A INPUT -p tcp --dport 477 -j DROP
nftables
sudo nft add rule inet filter input tcp dport 477 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block TCP 477' -Direction Inbound -Protocol TCP -LocalPort 477 -Action Block
ufw
sudo ufw deny 477/udp
iptables
sudo iptables -A INPUT -p udp --dport 477 -j DROP
nftables
sudo nft add rule inet filter input udp dport 477 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block UDP 477' -Direction Inbound -Protocol UDP -LocalPort 477 -Action Block

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