Port 1232 (first-defense)

IANA assigns port 1232 to first-defense: Remote systems monitoring.

Registered (user) port, 1024-49151 TCPUDP

IANA assignment

Service nameProtoDescriptionAssigneeReference

first-defense TCP Remote systems monitoring
Microsoft (unoffically) using 1232 Nexum -

first-defense UDP Remote systems monitoring
Microsoft (unoffically) using 1232 Nexum -

Registry dates for this port: registered 2012-09-21.

Linux: is anything listening on TCP 1232?

sudo ss -tlnp 'sport = :1232'

Linux: UDP 1232

sudo ss -ulnp 'sport = :1232'

Linux / macOS: which process owns the port

sudo lsof -nP -i :1232

Older Linux / BSD (net-tools)

sudo netstat -tlnp | grep ':1232 '

Windows (Command Prompt)

netstat -ano | findstr :1232

Windows (PowerShell)

Get-NetTCPConnection -LocalPort 1232 -State Listen | Select LocalAddress,OwningProcess

From another machine

nc -vz -w 5 HOST 1232

From Windows

Test-NetConnection HOST -Port 1232

UDP probe (no reply does not prove it is closed)

nc -vzu -w 5 HOST 1232

ufw

sudo ufw deny 1232/tcp

iptables

sudo iptables -A INPUT -p tcp --dport 1232 -j DROP

nftables

sudo nft add rule inet filter input tcp dport 1232 drop

Windows Firewall

New-NetFirewallRule -DisplayName 'Block TCP 1232' -Direction Inbound -Protocol TCP -LocalPort 1232 -Action Block

ufw

sudo ufw deny 1232/udp

iptables

sudo iptables -A INPUT -p udp --dport 1232 -j DROP

nftables

sudo nft add rule inet filter input udp dport 1232 drop

Windows Firewall

New-NetFirewallRule -DisplayName 'Block UDP 1232' -Direction Inbound -Protocol UDP -LocalPort 1232 -Action Block

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