Port 6379: Redis
What it is, why it matters and how to restrict it.
The default port of Redis. Redis was designed for trusted networks, and instances exposed to the internet without a password have been used to take over servers.
Secure it
Use the bind directive to limit interfaces, set a strong password or ACL users, and leave protected mode on. If other machines need Redis, allow only their addresses in the firewall.
Allow only one address on Linux
sudo iptables -I INPUT 1 -p tcp --dport 6379 -j DROP sudo iptables -I INPUT 1 -p tcp -s 203.0.113.5 --dport 6379 -j ACCEPT
The drop rule goes in first and the allow rule is inserted above it, so 203.0.113.5 is matched first. Replace it with your own address. With ufw, the equivalent allow rule is:
sudo ufw allow from 203.0.113.5 to any port 6379 proto tcp
Check from outside
nc -vz SERVER_IP 6379
Run it from an allowed address and from another one. A connection should succeed from the first and fail or time out from the second. Build custom rules with allow a port from specific IPs, or see all common ports.
FAQ
What is port 6379 used for?
Port 6379 is the default TCP port of Redis.
Should port 6379 be open to the internet?
Usually not. Keep it on localhost, behind a VPN, or limited to specific source IPs.
How do I block port 6379 for everyone except one IP?
Add an ACCEPT rule for that address, then a DROP rule for the port below it. The commands above do this in the correct order.