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Port 1643 (isis-ambc)

IANA assigns port 1643 to isis-ambc.

Registered (user) port, 1024-49151 TCPUDP

IANA assignment

Service nameProtoDescriptionAssigneeReference
isis-ambc TCP isis-ambc Ken Chapman -
isis-ambc UDP isis-ambc Ken Chapman -

Check what is listening on port 1643

Linux: is anything listening on TCP 1643?
sudo ss -tlnp 'sport = :1643'
Linux: UDP 1643
sudo ss -ulnp 'sport = :1643'
Linux / macOS: which process owns the port
sudo lsof -nP -i :1643
Older Linux / BSD (net-tools)
sudo netstat -tlnp | grep ':1643 '
Windows (Command Prompt)
netstat -ano | findstr :1643
Windows (PowerShell)
Get-NetTCPConnection -LocalPort 1643 -State Listen | Select LocalAddress,OwningProcess

Test it from outside

From another machine
nc -vz -w 5 HOST 1643
From Windows
Test-NetConnection HOST -Port 1643
UDP probe (no reply does not prove it is closed)
nc -vzu -w 5 HOST 1643

Block port 1643 in the firewall

ufw
sudo ufw deny 1643/tcp
iptables
sudo iptables -A INPUT -p tcp --dport 1643 -j DROP
nftables
sudo nft add rule inet filter input tcp dport 1643 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block TCP 1643' -Direction Inbound -Protocol TCP -LocalPort 1643 -Action Block
ufw
sudo ufw deny 1643/udp
iptables
sudo iptables -A INPUT -p udp --dport 1643 -j DROP
nftables
sudo nft add rule inet filter input udp dport 1643 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block UDP 1643' -Direction Inbound -Protocol UDP -LocalPort 1643 -Action Block

Related ports

1641invision1642isis-am1644saiseh1645sightline

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