Weird behavior with networking


New Member
Sep 28, 2019
This my first try at proxmox and I'm running into an issue. I've been reading and trying different things but nothing seems to resolve the error.

My proxmox machine has 2 nics 1 for WAN (enp0s25) and other for LAN (enp5s0). It also has 2 bridges: vmbr0(wan) and vmbr1(lan)

The configuration I'm looking for is
Internet > Proxmox > PfSense > everything else

When I boot (or even reboot) the machine, everything connected to the host has an internet connection BUT the host cannot access the internet. It also doesn't seem to set the NAT rules for iptables (so I think).
When I do
service networking restart
then the host has access to the internet and nothing else can access it. I dont know of any commands that would help with debugging this. The only real solution to getting everything back online is to simply restart the host.

Here is my /etc/networking/interfaces file

auto lo
iface lo inet loopback

allow-hotplug enp0s25

auto enp0s25
iface enp0s25 inet manual

auto enp5s0
iface enp5s0 inet manual

auto vmbr0
iface vmbr0 inet dhcp
        hwaddress ether  00:11:22:33:44:55
        bridge_ports enp0s25
        bridge_stp off
        bridge_fd 0

auto vmbr1
iface vmbr1 inet static
        bridge_ports enp5s0
        bridge_stp off
        bridge_fd 0
        post-up echo 1 > /proc/sys/net/ipv4/ip_forward
        post-up   iptables -t nat -A POSTROUTING -s '' -o vmbr0 -j MASQUERADE
        post-down iptables -t nat -D POSTROUTING -s '' -o vmbr0 -j MASQUERADE

I'm at a total loss with this. Any help would be appreciated
Last edited:

why do you set hwaddress?
Is the PFsense a VM or an External box?

why do you set hwaddress?
Is the PFsense a VM or an External box?

At some point when I was playing with proxmox, it set the hardware address. I know I dont need it. I just never took it out. Its identical to the associated nic
PFsense is a VM


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