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Port 28240 (siemensgsm)

IANA assigns port 28240 to siemensgsm: Siemens GSM.

Registered (user) port, 1024-49151 TCPUDP

IANA assignment

Service nameProtoDescriptionAssigneeReference
siemensgsm TCP Siemens GSM David Anuszewski -
siemensgsm UDP Siemens GSM David Anuszewski -

Registry dates for this port: registered 2004-11.

Check what is listening on port 28240

Linux: is anything listening on TCP 28240?
sudo ss -tlnp 'sport = :28240'
Linux: UDP 28240
sudo ss -ulnp 'sport = :28240'
Linux / macOS: which process owns the port
sudo lsof -nP -i :28240
Older Linux / BSD (net-tools)
sudo netstat -tlnp | grep ':28240 '
Windows (Command Prompt)
netstat -ano | findstr :28240
Windows (PowerShell)
Get-NetTCPConnection -LocalPort 28240 -State Listen | Select LocalAddress,OwningProcess

Test it from outside

From another machine
nc -vz -w 5 HOST 28240
From Windows
Test-NetConnection HOST -Port 28240
UDP probe (no reply does not prove it is closed)
nc -vzu -w 5 HOST 28240

Block port 28240 in the firewall

ufw
sudo ufw deny 28240/tcp
iptables
sudo iptables -A INPUT -p tcp --dport 28240 -j DROP
nftables
sudo nft add rule inet filter input tcp dport 28240 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block TCP 28240' -Direction Inbound -Protocol TCP -LocalPort 28240 -Action Block
ufw
sudo ufw deny 28240/udp
iptables
sudo iptables -A INPUT -p udp --dport 28240 -j DROP
nftables
sudo nft add rule inet filter input udp dport 28240 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block UDP 28240' -Direction Inbound -Protocol UDP -LocalPort 28240 -Action Block

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