HTTPfy

Port 4181 (macbak)

IANA assigns port 4181 to macbak: MacBak.

Registered (user) port, 1024-49151 TCPUDP

IANA assignment

Service nameProtoDescriptionAssigneeReference
macbak TCP MacBak Wes Peters -
macbak UDP MacBak Wes Peters -

Registry dates for this port: registered 2007-04.

Check what is listening on port 4181

Linux: is anything listening on TCP 4181?
sudo ss -tlnp 'sport = :4181'
Linux: UDP 4181
sudo ss -ulnp 'sport = :4181'
Linux / macOS: which process owns the port
sudo lsof -nP -i :4181
Older Linux / BSD (net-tools)
sudo netstat -tlnp | grep ':4181 '
Windows (Command Prompt)
netstat -ano | findstr :4181
Windows (PowerShell)
Get-NetTCPConnection -LocalPort 4181 -State Listen | Select LocalAddress,OwningProcess

Test it from outside

From another machine
nc -vz -w 5 HOST 4181
From Windows
Test-NetConnection HOST -Port 4181
UDP probe (no reply does not prove it is closed)
nc -vzu -w 5 HOST 4181

Block port 4181 in the firewall

ufw
sudo ufw deny 4181/tcp
iptables
sudo iptables -A INPUT -p tcp --dport 4181 -j DROP
nftables
sudo nft add rule inet filter input tcp dport 4181 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block TCP 4181' -Direction Inbound -Protocol TCP -LocalPort 4181 -Action Block
ufw
sudo ufw deny 4181/udp
iptables
sudo iptables -A INPUT -p udp --dport 4181 -j DROP
nftables
sudo nft add rule inet filter input udp dport 4181 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block UDP 4181' -Direction Inbound -Protocol UDP -LocalPort 4181 -Action Block

Related ports

4179MaxumSP4180httpx4182pcptcpservice4183cyborgnet

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