Find Cloud Firewall Logs to see what's being blocked
Hi All,
I'm running into an issue where one of my nodes stops allowing APT traffic when behind a Linode Cloud Firewall.
I have another Linode that works fine, but the new one fails updates every time it's behind the firewall. As soon as it's disabled, it all works again.
Is there any way to see the logs of the Cloud Firewall to see what's blocking?
Inbound
HTTP, HTTPS, DNS, SSH
ALL IPV4/IPV6
Outbound
HTTP, HTTPS, DNS
ALL IPV4/IPV6
Both nodes are Debian 11 and have no other FW installed/running.
2 Replies
✓ Best Answer
Legend thanks I completely forgot about UDP for DNS doh!
You don't say which of tcp/udp are open…both? tcp only? If 53/tcp is open, but 53/udp is closed, you will see this kind of failure.
DNS (port 53) primarily uses udp. It fails over to tcp during high-load conditions.
Just as a matter of preference, I'd allow outbound ssh as well. Some apps that you might install use it for updates (with a secure tunnel).
There are other ways to secure ssh (like disabling root logins from ssh sessions; only using public-key authentication; and disallowing passwords).
-- sw