Two NICs work on one guest, not on the other!

[Sam Salhi]

Hello all, new user, please go easy on me!

The proxmox server has 2 NICs
One connected to a private network with IPs assigned by DHCP. Works great in all guests
Second NIC is connected to a public network and the guests must have static IPs for it.

The problem is that the NICs for public IP work for only ONE guest ONLY! They can be accessed remotely with no problem.
When I added a second guest, no connections can be made ti the guest through the public NIC

Can someone help me? Where did I go wrong?

 

[Sam Salhi]

Anyone?

 

[Sam Salhi]

I think I'm ready to quit proxmox ... configuring what is normally a trivial network in just about any other virtual environment is such a painful task. I literally tried everything to enable this simple situation. One macine, two nics, one connected to the internal network, one to the public network
The internal network has DHCP external has mutiple static IPs!
This should work with ease. But for the life of me, I just can't get it to work!

Did anyone try this? Can anyone help?

 

[Richard]

One macine, two nics, one connected to the internal network, one to the public network
The internal network has DHCP external has mutiple static IPs!
This should work with ease. But for the life of me, I just can't get it to work!

For Proxmox it does not make any difference whether the network is an internal or public one. If the public address works at a certain (physical or virtual) NIC depends last but not least on provider's configuration. Make sure

- that the public address you want to use is dedicated to you

- that the NICs MAC address is accepted by the provider


You did not post any further details; however: experience says the second case is more probable, providers have usually restrictions which MAC addresses you may use.

Proxmox (host and guests) work correctly (without active firewall)

- if pings from public to public IPs within your environment are possible

- packets from the guests can be seen at the host's public interface but no responses to them

 

[Sam Salhi]

Thank you Richard
1. There are no MAC address restrictions.
2. No firewall enabled
3. Pings from public to public don't work
4. Packets from guests can not reach public interface

This same exact setup, sans proxmox ve, worked flawlessly with VirtualBox. Right now, only the private network works. Not the public one!
The public one doesn't even work internal to Proxmox.

Would you please help me? Is there a "Standard" type of setup that serves this case? I tried everything

Regards
Sam

 

[Richard]

4. Packets from guests can not reach public interface

Look like wrong network settings inside the guest. Did it get the public IP via DHCP?

Try to follow the packets from inside the guest via virtual interfaces on their way to destination.

Step 1: inside the guest

Step 2: virtual NIC in Proxmox VE which provides connectivity to the guest, the name is constructed as follows:

tap<vm-id>i<net-number>; e.g. tap101i1

Step3: at the VE bridge; e.g. vmbr0

Step4: at the physical public interface, e.g. enx00e04b68384a

You read the packets by

tcpdump -e -n -i vmbr0

etc.

Works in Linux, if your guest is Windows use wireshark there.

 

[Sam Salhi]

Thanks again Richard, It's virtually impossible to have wrong settings on the guest. They run windows and have correct settings 100% I have validated this many many times.
There is something wrong unfortunately with Proxmox virtual bridge! I'm not sure if it's a bug or something else.

Thanks again Richard for your fantastic support!

 

[Sam Salhi]

Step 2: virtual NIC in Proxmox VE which provides connectivity to the guest, the name is constructed as follows:

tap<vm-id>i<net-number>; e.g. tap101i1

Can you expand some more on this point?

We might be on to something new that I have not tried

 

[Sam Salhi]

I finally figured it out!!
I had installed a second USB based Ethernet adapter!
I made the mistake of assigning that USB interface to one of the guest computers. Whenever this guest was down, the network would work fine for other guests. But the minute that guest comes back online, all other guests and the bridge lose network connectivity because that one guest has taken over the USB port all by itself and even though it has Public network through the USB interface. That ethernet can no longer be virtualized by Proxmox VE and provided to others!
Such a weird issue!! But I'm so glad it is fixed.

 

[Belokan]

More a weird configuration than a weird issue, but glad you've finally found what was wrong your environment before "quitting proxmox" which is a really good piece of software

 

[Sam Salhi]

What can you say ... I'm new to Proxmox after 10 years of hypervisor and 7 years of VirtualBox ... this is HARD WORK