Is it safe to open
Infrastructure services (DNS, NTP, DHCP, routing) should answer only the networks they serve. Open resolvers and time servers get abused for DDoS amplification.
How to open port 179
Open to everyone
# Linux iptables iptables -A INPUT -p tcp --dport 179 -j ACCEPT # Ubuntu ufw ufw allow 179/tcp # firewalld firewall-cmd --permanent --add-port=179/tcp && firewall-cmd --reload # MikroTik /ip firewall filter add chain=input protocol=tcp dst-port=179 action=accept place-before=0 comment="port 179" # Windows (PowerShell) New-NetFirewallRule -DisplayName "Port 179 TCP" -Direction Inbound -Protocol TCP -LocalPort 179 -Action Allow
Only for your addresses
# allow only one address or network (replace 203.0.113.0/24) iptables -A INPUT -p tcp --dport 179 -s 203.0.113.0/24 -j ACCEPT iptables -A INPUT -p tcp --dport 179 -j DROP ufw allow from 203.0.113.0/24 to any port 179 proto tcp /ip firewall filter add chain=input protocol=tcp dst-port=179 src-address=203.0.113.0/24 action=accept /ip firewall filter add chain=input protocol=tcp dst-port=179 action=drop
If the server is behind a router, you also need a port forward (dst-nat). Behind ISP CGNAT (100.64.0.0/10 on the WAN) forwarding will not help: you need a public IP or a VPN.
What is listening
Check on the server
# what listens on the port ss -lntup | grep ':179 ' netstat -ano | findstr :179 # Windows lsof -i :179 # macOS # test from another machine nc -vz example.com 179