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Port 245 (link)

IANA assigns port 245 to link: LINK.

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

IANA assignment

Service nameProtoDescriptionAssigneeReference
link TCP LINK - -
link UDP LINK - -

Check what is listening on port 245

Linux: is anything listening on TCP 245?
sudo ss -tlnp 'sport = :245'
Linux: UDP 245
sudo ss -ulnp 'sport = :245'
Linux / macOS: which process owns the port
sudo lsof -nP -i :245
Older Linux / BSD (net-tools)
sudo netstat -tlnp | grep ':245 '
Windows (Command Prompt)
netstat -ano | findstr :245
Windows (PowerShell)
Get-NetTCPConnection -LocalPort 245 -State Listen | Select LocalAddress,OwningProcess

Test it from outside

From another machine
nc -vz -w 5 HOST 245
From Windows
Test-NetConnection HOST -Port 245
UDP probe (no reply does not prove it is closed)
nc -vzu -w 5 HOST 245

Block port 245 in the firewall

ufw
sudo ufw deny 245/tcp
iptables
sudo iptables -A INPUT -p tcp --dport 245 -j DROP
nftables
sudo nft add rule inet filter input tcp dport 245 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block TCP 245' -Direction Inbound -Protocol TCP -LocalPort 245 -Action Block
ufw
sudo ufw deny 245/udp
iptables
sudo iptables -A INPUT -p udp --dport 245 -j DROP
nftables
sudo nft add rule inet filter input udp dport 245 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block UDP 245' -Direction Inbound -Protocol UDP -LocalPort 245 -Action Block

Related ports

243sur-meas244inbusiness246dsp3270247subntbcst-tftp, subntbcst_tftp

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