Proxmox: how to route traffic to CTs (VMs)

Aleksandr Muravja

6/15/24, 8:11 PM

I have Promox server with 3 IPs (Main IP and 2 additional ones). Server has 3 CTs and I want to assign all 3 IPs to those CTs.

Assinging them directly to CTs/VMs didn't work (even gateway is not accessible). So I did NAT1:1 with -j NETMAP.

From outside it works correctly, but I cannot connect between each CTs using their external IP address.

Configuration:

All CTs/VMs are connected to both vmbr0 (external static IPv6) and vmbr1 (internal static IPv4).

iface ens3 inet manual

auto vmbr0
iface vmbr0 inet static
    address 176.X.Y.Z/24 #Main IP
    gateway 176.X.Y.GW
    bridge-ports ens3
    bridge-stp off
    bridge-fd 1
# InterNet

iface vmbr0 inet6 static
    address <ip6_subnet_here>::1/64
    gateway fe80::1

        post-up   /srv/bin/router-up.sh
        post-down /srv/bin/router-down.sh

auto vmbr0:1
iface vmbr0:1 inet static
    address 31.A.B.C/24 # First additional IP

auto vmbr0:5
iface vmbr0:5 inet static
    address 31.A.B.D/24 # Second additional IP

IPTables rules for NAT are here /srv/bin/router-up.sh

-A PREROUTING -d 176.X.Y.Z/32 -j NETMAP --to 192.168.1.25/32 #192.168.1.25 is CT1 IP in vmbr1
-A PREROUTING -d 31.A.B.C/32 -j NETMAP --to 192.168.1.9/32 #192.168.1.9 is CT2 IP in vmbr1
-A PREROUTING -d 31.A.B.D/32 -j NETMAP --to 192.168.1.2/32 #192.168.1.2 is CT3 IP in vmbr1
-A POSTROUTING -s 192.168.1.25/32 -j NETMAP --to 176.X.Y.Z/32
-A POSTROUTING -s 192.168.1.9/32 -j NETMAP --to 31.A.B.C/32
-A POSTROUTING -s 192.168.1.2/32 -j NETMAP --to 31.A.B.D/32

/srv/bin/router-down.sh just deletes those rules.

Please suggest how to change configuration to be able to connect from each CT/VM to others (using external IP). Thanks.

0 + 1

nat

routing

iptables

proxmox

A.B

6/16/24, 9:07 AM

suggestion so you understand the problem: https://en.wikipedia.org/wiki/Network_address_translation#NAT_loopback

Elon Musk

I sit in a Tesla and translated this thread with Ai:

EN: Proxmox: how to route traffic to CTs (VMs)

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