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Port 4980 (ctxs-vpp)

IANA assigns port 4980 to ctxs-vpp: Citrix Virtual Path.

Registered (user) port, 1024-49151 UDP

Port 4980 is normally used over UDP; the checker tests TCP only, so a "filtered" result does not mean the UDP service is down.

IANA assignment

Service nameProtoDescriptionAssigneeReference
ctxs-vpp UDP Citrix Virtual Path Citrix Systems -

Registry dates for this port: registered 2015-04-17.

Check what is listening on port 4980

Linux: UDP 4980
sudo ss -ulnp 'sport = :4980'
Linux / macOS: which process owns the port
sudo lsof -nP -i :4980
Windows (Command Prompt)
netstat -ano | findstr :4980
Windows (PowerShell)
Get-NetUDPEndpoint -LocalPort 4980

Test it from outside

UDP probe (no reply does not prove it is closed)
nc -vzu -w 5 HOST 4980

Block port 4980 in the firewall

ufw
sudo ufw deny 4980/udp
iptables
sudo iptables -A INPUT -p udp --dport 4980 -j DROP
nftables
sudo nft add rule inet filter input udp dport 4980 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block UDP 4980' -Direction Inbound -Protocol UDP -LocalPort 4980 -Action Block

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