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Port 4671 (acter)

IANA assigns port 4671 to acter: Bull RSF action server.

Registered (user) port, 1024-49151 TCPUDP

IANA assignment

Service nameProtoDescriptionAssigneeReference
acter TCP Bull RSF action server Christian Caudrelier -
acter UDP Bull RSF action server Christian Caudrelier -

Registry dates for this port: registered 2006-02.

Check what is listening on port 4671

Linux: is anything listening on TCP 4671?
sudo ss -tlnp 'sport = :4671'
Linux: UDP 4671
sudo ss -ulnp 'sport = :4671'
Linux / macOS: which process owns the port
sudo lsof -nP -i :4671
Older Linux / BSD (net-tools)
sudo netstat -tlnp | grep ':4671 '
Windows (Command Prompt)
netstat -ano | findstr :4671
Windows (PowerShell)
Get-NetTCPConnection -LocalPort 4671 -State Listen | Select LocalAddress,OwningProcess

Test it from outside

From another machine
nc -vz -w 5 HOST 4671
From Windows
Test-NetConnection HOST -Port 4671
UDP probe (no reply does not prove it is closed)
nc -vzu -w 5 HOST 4671

Block port 4671 in the firewall

ufw
sudo ufw deny 4671/tcp
iptables
sudo iptables -A INPUT -p tcp --dport 4671 -j DROP
nftables
sudo nft add rule inet filter input tcp dport 4671 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block TCP 4671' -Direction Inbound -Protocol TCP -LocalPort 4671 -Action Block
ufw
sudo ufw deny 4671/udp
iptables
sudo iptables -A INPUT -p udp --dport 4671 -j DROP
nftables
sudo nft add rule inet filter input udp dport 4671 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block UDP 4671' -Direction Inbound -Protocol UDP -LocalPort 4671 -Action Block

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