I wanted to implement my “standard firewall” also to my Discourse VM’s to enable traffic to the SSH port only from my approved IP’s. So I’ve enabled any outgoing traffic from my VM and enabled incoming for ports 443, 80 and 22 (last is limited to my approved IPs).
All works quite well, but then I’ve noticed that my outgoing emails to my email server are not working at all. Crazy enough as I’ve allowed outgoing connections from my VM.
My firewall setup includes the interfaces which I find with ifconfig:
- eth0: Main interface to the outside world, that’s my public IP
- docker0: Seems to be created by Discourse, IP 172.17.0.1/16. Not a real idea what’s the purpose of this (virtual) interface?!?
- lo (as usual …)
Any ideas what’s wrong here?