Port 80 outbound not working for guests or host

xyleth

New Member
Jan 19, 2024
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This one is really weird.

Everything on my Proxmox host is suffering from this. CTs, VMs, even docker containers running on those VMs have the same issue and I'm tearing what little remains of my hair out over it. The same issue affects the host if I open the console and test there.

They are all completely unable to make an outbound connection on port 80, standard HTTP. 443/HTTPS works fine, but 80 just times out every time. I first noticed this because apt wasn't working on my Ubuntu VMs. Changing apt to use https instead of http, works fine. But http - no dice.

This is a vanilla home lab style Proxmox 8.1.3 install on a HP DeskPro machine. Single NIC configured as the default bridge (vmbr0). The firewall is disabled at the data centre level. All other networking functions work fine. I can ping, resolve names, trace routes, connect to any other port but 80 to my hearts content. It is just this one thing and it is crippling because every package system seems to default to HTTP. Containers won't build right, install scripts fail, all sorts.

Does anyone have any ideas why this might be the case? Happy to run any diagnostics / post more information if it'll help but I'm out of ideas here.
 
okay, heaven knows what was causing it but restarting my ISP supplied router has resolved the issue!
 
I have a similar problem, and it only affects IPv4. There is no router I can restart ;-(
Oops. It was my own iptables Rule in the PVE node, as in "iptables -t nat -L PREROUTING ... DNAT ....".

I'm still wondering why that effects guests that go through other guests to connect to the IPv4 world. I used to believe the network namespaces of the different cgroups would totally isolate the network stacks from each other, seems I'm wrong.

There are kernel experts I meet every now and then, but they turn away when I mention I'm using a kernel "tampered with" by someone else ...