Unable to Access Proxmox Web GUI

[genaut]

Hi all,

I’m running a Proxmox VE server with IP 192.168.1.81 (static, and enable static ip to his MAC in my router) configured static on the vmbr0 bridge interface. The system has been working fine until recently, but now I can’t access the web GUI from any other device on the local network.

Inside proxmox (I only can access physically plugin in a keyboard, no ssh, no web..) I have a TRUENAS vm with plex, plex it's on 192.168.1.91 and working fine.. Anyway, I can't access to my truenas machine using his IP, only my no-ip domain associated to IP+port (weird?)

To be honest, yesterday, my network cable in the room where I had the set up stop working and I just moved the server to other room and plugged in other network cable (to the same router). After this, I didn't connect to the web interface, anyway, I am not sure if it is related.

Here’s the situation and what I’ve checked so far:

• The Proxmox host is reachable via ping from other devices, and ping replies are consistent and fast. I can ping from proxmox to my windows machine without problems.
• The web proxy service (pveproxy) is running and listening on all interfaces on port 8006.
• I can run curl -vk https://localhost:8006 or https://192.168.1.81:8006/ directly on the Proxmox host, and it returns the HTML content of the web interface.
• From another machine on the network:
  • Test-NetConnection 192.168.1.81 -Port 8006 returns TcpTestSucceeded: True.
  • However, opening https://192.168.1.81:8006 in any browser immediately results in ERR_CONNECTION_CLOSED. (I tested in private browser mode too)
  • No SSL warnings or certificate errors appear; the connection just closes.
• SSH is running and listening on port 22, and the TCP TcpTestSucceeded is true too but PuTTY connection fail (remote host close the connection).
• The router hasn't VLAN configuration enabled and the router firewall is disbaled now.
• The Proxmox firewall (pve-firewall) is disabled, and iptables rules are empty.
• Logs (journalctl -u pveproxy) show no relevant errors when trying to connect, only repeated “detected empty handle” messages, which seem unrelated.
• I’ve tried restarting pveproxy and restarting the server without success.
• Running pveproxy manually with --debug to catch logs doesn’t show any new information on connection attempts.

The biggest mystery is that the TCP handshake succeeds but the connection closes immediately before any HTTP data is sent. The Proxmox GUI service seems up and responsive locally but inaccessible externally. Some days ago, I could enter without problems (I didnt remember when).

Has anyone experienced something similar or can suggest further debugging steps?

Thanks in advance! Sorry my english

 

[Ruprecht]

Hello @genaut ,

as I am working on solution on the same (or very very similar) issue, I decided to let you know about workaround I am testing right at this time.
Try to add to iptables rules to achieve DNAT from other port - I used 8007 and set DNAT on the proxmox host to the port 8006:

iptables -t nat -A PREROUTING -p tcp -s 192.168.0.0/16 --dport 8007 -j DNAT --to <your actual proxmox IP address>:8006
iptables -t nat -A POSTROUTING -p tcp -s 192.168.0.0/16 --dport 8006 -j MASQUERADE

With this WORKAROUND, I was able to get some http source in browser, but result still was not as expected.
Logically, to test it, you have to change the URL in your browser to port 8007: https://<ip addr of proxmox>:8007 instead of 8006.

Please let me know if it changes behavior of your proxmox installation, thx

 

[Ruprecht]

Just note for you. I just find here in forum this thread , I am just reeding it right now and it looks like you could be interested in. Their web source looks like the one i get after DNAT workaround described.

edit: New thread created to better tracking.