apt-get update issues...

So, I've been fighting with my Kali box trying to get apt-get update to... well... update. I've tried everything I can, and I think I've narrowed it down to either some weird issue with the proxy (although in my logs, it's showing the traffic as allowed,) or the repos are having issues...

When I run apt-get update (with or without --fix-missing), it seems to chug along fine, then will give me the (Waiting on headers... 100%) and stick there for a minute before returning something like

Err http:/security.kali.org kali/updates/contrib amd64 Packages

Further down the line I get some

Err http://security.kali.org kali/updates/non-free amd64 Packages
503 Service Unavailable

And finally

W: Failed to fetch http://security.kali.org/kali-securi...amd64/Packages 503 Service Unavailable.

I tried running Wireshark on the box, but all the traffic is just going to and from the proxy, and doesn't give me any more information (I still see the 503 errors in the response packets from the proxy.)

All the logs I see in the SIEM say the traffic was allowed through the webfilter (proxy,) and even the firewall logs show that it was allowed based on a rule.

Are there any logs on the machine itself I can look at to figure what's going on? Or does anyone know what I could do to fix this? In my google searching I found another thread here about 404 errors at https://forums.kali.org/showthread.p...-404-Not-found but the fix posted by djhbjxc doesn't seem to work for my case.

Alright, I finally tracked down the problem. Apparently our automated IP reputation system had put one of the kali.org IPs into its auto-block list that gets imported by the firewall, so the firewall was dropping the traffic. One of the main repository IPs apparently got flagged at AlienVault as a malware domain. Weird, but everything is working as per normal again.