What can cause SSL/443 port blocking regularly within a specific timeline?

Question

I run on CentOS 6.x in dedicated rackspace cloud hosting and recently I installed SSL and enabled https access for my website. 443 port is enabled in iptables and APF firewall as well. But every 18-20 hours HTTPS suddenly gets blocked(http and 80 port always OK) and only after restating APF firewall makes https accessible again. After the restart it lasts for another 20 hours and again the same thing happening regularly. I tried to stop APF suspecting it causing the issue but something else looks still causing it. I suspect iptables may cause it but unfortunately have no idea how to track the issue down.

Any help or direction will be highly appreciated.

Thanks.

apf restarts by itself from time to time. I think it has a configuration doing so. Just remove it and replace it with csf. Don't use both iptables and apf/csf as they manage the same thing (Linux kernel netfilters), use just one of them. — Florin Asăvoaie, Jan 10 '18 at 21:28
@FlorinAsăvoaie CSF and APF are management scripts for iptables so you use either CSF or APF with iptables, but not both. — Simon Greenwood, Jan 10 '18 at 22:57
Many thanks for the direction. I will uninstall APF and try CSF. — taras, Jan 11 '18 at 08:35

score 1 · Answer 1 · answered Jan 10 '18 at 23:06

I believe (but I can't really prove it) that this is an issue with upstream routing in some providers. I manage a large number of machines using apf, many of which are at one particular provider, and these machines have no problems. Other similarly configured machines at other providers have done in the past, and we never managed to find a cause on the servers apart from restarting iptables fixing the issue. It was always HTTPS on port 443 and never HTTP, so I think it must be either in an upstream firewall or router and is affected by a firewall being reloaded, which would suggest something to do with arp or other mechanisms at that level.

What can cause SSL/443 port blocking regularly within a specific timeline?

1 Answers1