Allow webapps to make outgoing requests

I was experiencing a pretty bad slowdown while trying to use the admin pages of a WordPress site recently. The load on the machine was quite low, so I began to suspect that it was trying to call out to external services (facebook, pinterest, etc) that might have been blocked by CSF (configserver firewall).

I started playing around with tcpdump and friends and then realized that the information I was looking for (blocked outgoing requests) was already being logged in /var/log/kern.log on our Ubuntu system (same on Debian).

Here’s the little pipeline I used to look up the hostnames of the requests that were blocked:

It could be formatted nicer, but at least it gave me what I wanted. After removing an erroneous firewall entry using csf -dr IP[/CIDR|NETMASK], all was snappy once again.