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Port 508 (xvttp)

IANA assigns port 508 to xvttp.

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

IANA assignment

Service nameProtoDescriptionAssigneeReference
xvttp TCP xvttp Keith J Alphonso -
xvttp UDP xvttp Keith J Alphonso -

Check what is listening on port 508

Linux: is anything listening on TCP 508?
sudo ss -tlnp 'sport = :508'
Linux: UDP 508
sudo ss -ulnp 'sport = :508'
Linux / macOS: which process owns the port
sudo lsof -nP -i :508
Older Linux / BSD (net-tools)
sudo netstat -tlnp | grep ':508 '
Windows (Command Prompt)
netstat -ano | findstr :508
Windows (PowerShell)
Get-NetTCPConnection -LocalPort 508 -State Listen | Select LocalAddress,OwningProcess

Test it from outside

From another machine
nc -vz -w 5 HOST 508
From Windows
Test-NetConnection HOST -Port 508
UDP probe (no reply does not prove it is closed)
nc -vzu -w 5 HOST 508

Block port 508 in the firewall

ufw
sudo ufw deny 508/tcp
iptables
sudo iptables -A INPUT -p tcp --dport 508 -j DROP
nftables
sudo nft add rule inet filter input tcp dport 508 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block TCP 508' -Direction Inbound -Protocol TCP -LocalPort 508 -Action Block
ufw
sudo ufw deny 508/udp
iptables
sudo iptables -A INPUT -p udp --dport 508 -j DROP
nftables
sudo nft add rule inet filter input udp dport 508 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block UDP 508' -Direction Inbound -Protocol UDP -LocalPort 508 -Action Block

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