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Port 6801 (acnet)

IANA assigns port 6801 to acnet: ACNET Control System Protocol.

Registered (user) port, 1024-49151 TCPUDP

IANA assignment

Service nameProtoDescriptionAssigneeReference
acnet TCP ACNET Control System Protocol Fermilab -
acnet UDP ACNET Control System Protocol Fermilab -

Registry dates for this port: registered 2007-02, last modified 2017-07-13.

Check what is listening on port 6801

Linux: is anything listening on TCP 6801?
sudo ss -tlnp 'sport = :6801'
Linux: UDP 6801
sudo ss -ulnp 'sport = :6801'
Linux / macOS: which process owns the port
sudo lsof -nP -i :6801
Older Linux / BSD (net-tools)
sudo netstat -tlnp | grep ':6801 '
Windows (Command Prompt)
netstat -ano | findstr :6801
Windows (PowerShell)
Get-NetTCPConnection -LocalPort 6801 -State Listen | Select LocalAddress,OwningProcess

Test it from outside

From another machine
nc -vz -w 5 HOST 6801
From Windows
Test-NetConnection HOST -Port 6801
UDP probe (no reply does not prove it is closed)
nc -vzu -w 5 HOST 6801

Block port 6801 in the firewall

ufw
sudo ufw deny 6801/tcp
iptables
sudo iptables -A INPUT -p tcp --dport 6801 -j DROP
nftables
sudo nft add rule inet filter input tcp dport 6801 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block TCP 6801' -Direction Inbound -Protocol TCP -LocalPort 6801 -Action Block
ufw
sudo ufw deny 6801/udp
iptables
sudo iptables -A INPUT -p udp --dport 6801 -j DROP
nftables
sudo nft add rule inet filter input udp dport 6801 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block UDP 6801' -Direction Inbound -Protocol UDP -LocalPort 6801 -Action Block

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