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Port 23401 (novar-alarm)

IANA assigns port 23401 to novar-alarm: Novar Alarm.

Registered (user) port, 1024-49151 TCPUDP

IANA assignment

Service nameProtoDescriptionAssigneeReference
novar-alarm TCP Novar Alarm Keith Kilroy -
novar-alarm UDP Novar Alarm Keith Kilroy -

Registry dates for this port: registered 2006-02.

Check what is listening on port 23401

Linux: is anything listening on TCP 23401?
sudo ss -tlnp 'sport = :23401'
Linux: UDP 23401
sudo ss -ulnp 'sport = :23401'
Linux / macOS: which process owns the port
sudo lsof -nP -i :23401
Older Linux / BSD (net-tools)
sudo netstat -tlnp | grep ':23401 '
Windows (Command Prompt)
netstat -ano | findstr :23401
Windows (PowerShell)
Get-NetTCPConnection -LocalPort 23401 -State Listen | Select LocalAddress,OwningProcess

Test it from outside

From another machine
nc -vz -w 5 HOST 23401
From Windows
Test-NetConnection HOST -Port 23401
UDP probe (no reply does not prove it is closed)
nc -vzu -w 5 HOST 23401

Block port 23401 in the firewall

ufw
sudo ufw deny 23401/tcp
iptables
sudo iptables -A INPUT -p tcp --dport 23401 -j DROP
nftables
sudo nft add rule inet filter input tcp dport 23401 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block TCP 23401' -Direction Inbound -Protocol TCP -LocalPort 23401 -Action Block
ufw
sudo ufw deny 23401/udp
iptables
sudo iptables -A INPUT -p udp --dport 23401 -j DROP
nftables
sudo nft add rule inet filter input udp dport 23401 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block UDP 23401' -Direction Inbound -Protocol UDP -LocalPort 23401 -Action Block

Related ports

23333elxmgmt23400novar-dbase23402novar-global23456aequus

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