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Port 1171 (atc-appserver)

IANA assigns port 1171 to atc-appserver: AT+C FmiApplicationServer.

Registered (user) port, 1024-49151 TCPUDP

IANA assignment

Service nameProtoDescriptionAssigneeReference
atc-appserver TCP AT+C FmiApplicationServer Peter Schafer -
atc-appserver UDP AT+C FmiApplicationServer Peter Schafer -

Registry dates for this port: registered 2004-02.

Check what is listening on port 1171

Linux: is anything listening on TCP 1171?
sudo ss -tlnp 'sport = :1171'
Linux: UDP 1171
sudo ss -ulnp 'sport = :1171'
Linux / macOS: which process owns the port
sudo lsof -nP -i :1171
Older Linux / BSD (net-tools)
sudo netstat -tlnp | grep ':1171 '
Windows (Command Prompt)
netstat -ano | findstr :1171
Windows (PowerShell)
Get-NetTCPConnection -LocalPort 1171 -State Listen | Select LocalAddress,OwningProcess

Test it from outside

From another machine
nc -vz -w 5 HOST 1171
From Windows
Test-NetConnection HOST -Port 1171
UDP probe (no reply does not prove it is closed)
nc -vzu -w 5 HOST 1171

Block port 1171 in the firewall

ufw
sudo ufw deny 1171/tcp
iptables
sudo iptables -A INPUT -p tcp --dport 1171 -j DROP
nftables
sudo nft add rule inet filter input tcp dport 1171 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block TCP 1171' -Direction Inbound -Protocol TCP -LocalPort 1171 -Action Block
ufw
sudo ufw deny 1171/udp
iptables
sudo iptables -A INPUT -p udp --dport 1171 -j DROP
nftables
sudo nft add rule inet filter input udp dport 1171 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block UDP 1171' -Direction Inbound -Protocol UDP -LocalPort 1171 -Action Block

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