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Port 510 (fcp)

IANA assigns port 510 to fcp: FirstClass Protocol.

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

IANA assignment

Service nameProtoDescriptionAssigneeReference
fcp TCP FirstClass Protocol Mike Marshburn -
fcp UDP FirstClass Protocol Mike Marshburn -

Check what is listening on port 510

Linux: is anything listening on TCP 510?
sudo ss -tlnp 'sport = :510'
Linux: UDP 510
sudo ss -ulnp 'sport = :510'
Linux / macOS: which process owns the port
sudo lsof -nP -i :510
Older Linux / BSD (net-tools)
sudo netstat -tlnp | grep ':510 '
Windows (Command Prompt)
netstat -ano | findstr :510
Windows (PowerShell)
Get-NetTCPConnection -LocalPort 510 -State Listen | Select LocalAddress,OwningProcess

Test it from outside

From another machine
nc -vz -w 5 HOST 510
From Windows
Test-NetConnection HOST -Port 510
UDP probe (no reply does not prove it is closed)
nc -vzu -w 5 HOST 510

Block port 510 in the firewall

ufw
sudo ufw deny 510/tcp
iptables
sudo iptables -A INPUT -p tcp --dport 510 -j DROP
nftables
sudo nft add rule inet filter input tcp dport 510 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block TCP 510' -Direction Inbound -Protocol TCP -LocalPort 510 -Action Block
ufw
sudo ufw deny 510/udp
iptables
sudo iptables -A INPUT -p udp --dport 510 -j DROP
nftables
sudo nft add rule inet filter input udp dport 510 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block UDP 510' -Direction Inbound -Protocol UDP -LocalPort 510 -Action Block

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