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Port 2740 (alarm)

IANA assigns port 2740 to alarm: Alarm.

Registered (user) port, 1024-49151 TCPUDP

IANA assignment

Service nameProtoDescriptionAssigneeReference
alarm TCP Alarm Uriy Makasjuk -
alarm UDP Alarm Uriy Makasjuk -

Check what is listening on port 2740

Linux: is anything listening on TCP 2740?
sudo ss -tlnp 'sport = :2740'
Linux: UDP 2740
sudo ss -ulnp 'sport = :2740'
Linux / macOS: which process owns the port
sudo lsof -nP -i :2740
Older Linux / BSD (net-tools)
sudo netstat -tlnp | grep ':2740 '
Windows (Command Prompt)
netstat -ano | findstr :2740
Windows (PowerShell)
Get-NetTCPConnection -LocalPort 2740 -State Listen | Select LocalAddress,OwningProcess

Test it from outside

From another machine
nc -vz -w 5 HOST 2740
From Windows
Test-NetConnection HOST -Port 2740
UDP probe (no reply does not prove it is closed)
nc -vzu -w 5 HOST 2740

Block port 2740 in the firewall

ufw
sudo ufw deny 2740/tcp
iptables
sudo iptables -A INPUT -p tcp --dport 2740 -j DROP
nftables
sudo nft add rule inet filter input tcp dport 2740 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block TCP 2740' -Direction Inbound -Protocol TCP -LocalPort 2740 -Action Block
ufw
sudo ufw deny 2740/udp
iptables
sudo iptables -A INPUT -p udp --dport 2740 -j DROP
nftables
sudo nft add rule inet filter input udp dport 2740 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block UDP 2740' -Direction Inbound -Protocol UDP -LocalPort 2740 -Action Block

Related ports

2738ndl-tcp-ois-gw2739tn-timing2741tsb2742tsb2

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