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Port 2517 (call-sig-trans)

IANA assigns port 2517 to call-sig-trans: H.323 Annex E Call Control Signalling Transport.

Registered (user) port, 1024-49151 TCPUDP

IANA assignment

Service nameProtoDescriptionAssigneeReference
call-sig-trans TCP H.323 Annex E Call Control Signalling Transport ITU-T -
call-sig-trans UDP H.323 Annex E Call Control Signalling Transport ITU-T -

Registry dates for this port: last modified 2013-01-31.

Check what is listening on port 2517

Linux: is anything listening on TCP 2517?
sudo ss -tlnp 'sport = :2517'
Linux: UDP 2517
sudo ss -ulnp 'sport = :2517'
Linux / macOS: which process owns the port
sudo lsof -nP -i :2517
Older Linux / BSD (net-tools)
sudo netstat -tlnp | grep ':2517 '
Windows (Command Prompt)
netstat -ano | findstr :2517
Windows (PowerShell)
Get-NetTCPConnection -LocalPort 2517 -State Listen | Select LocalAddress,OwningProcess

Test it from outside

From another machine
nc -vz -w 5 HOST 2517
From Windows
Test-NetConnection HOST -Port 2517
UDP probe (no reply does not prove it is closed)
nc -vzu -w 5 HOST 2517

Block port 2517 in the firewall

ufw
sudo ufw deny 2517/tcp
iptables
sudo iptables -A INPUT -p tcp --dport 2517 -j DROP
nftables
sudo nft add rule inet filter input tcp dport 2517 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block TCP 2517' -Direction Inbound -Protocol TCP -LocalPort 2517 -Action Block
ufw
sudo ufw deny 2517/udp
iptables
sudo iptables -A INPUT -p udp --dport 2517 -j DROP
nftables
sudo nft add rule inet filter input udp dport 2517 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block UDP 2517' -Direction Inbound -Protocol UDP -LocalPort 2517 -Action Block

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