No Internet access on guest vm because of routing problems

C

CentrixDE

Active Member
Sep 3, 2017
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Hello,

I'm using the following setup:
Host Server with the following IPs

Public IP: 136.243.79.238
Additional IPs: 136.243.79.208
136.243.79.209
136.243.79.210
136.243.79.221

Network Setup: Routed like in the following guide (I know, that the instructions are a bit outdated but I didn't saw any real changes on other configuration examples posted with newer versions of proxmox):
https://community.hetzner.com/tutorials/install-and-configure-proxmox_ve


i'm currently trying to connect my vms to the internet.
I tested it with Debian 10 and can't find the error.

I can ping my guest VM with my host and the other way.
But it seems that there is a routing problem.

Here are my Configs:
Code: 
auto lo
iface lo inet loopback

auto ens18
iface ens18 inet static
      address 136.243.79.221
      netmask 255.255.255.255
      pointtopoint 136.243.79.238
      gateway 136.243.79.238
Code: 
auto eno1
iface eno1 inet static
  address  136.243.79.238
  netmask  255.255.255.192
  gateway  136.243.79.193
  post-up echo 1 > /proc/sys/net/ipv4/ip_forward
  post-up echo 1 > /proc/sys/net/ipv4/conf/eno1/proxy_arp
  # route 136.243.79.192/26 via 136.243.79.193
  up route add -net 136.243.79.192 netmask 255.255.255.192 gw 136.243.79.193 dev eno1

auto vmbr0
iface vmbr0 inet static
  address 136.243.79.238
  netmask 255.255.255.255
  bridge_ports none
  bridge_stp off
  bridge_fd 0
  up ip route add 136.243.79.208/32 dev vmbr0
  up ip route add 136.243.79.209/32 dev vmbr0
  up ip route add 136.243.79.210/32 dev vmbr0
  up ip route add 136.243.79.221/32 dev vmbr0
Code: 
root@host01 ~ # route -n
Kernel IP routing table
Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
0.0.0.0         136.243.79.193  0.0.0.0         UG    0      0        0 eno1
136.243.79.192  136.243.79.193  255.255.255.192 UG    0      0        0 eno1
136.243.79.192  0.0.0.0         255.255.255.192 U     0      0        0 eno1
136.243.79.208  0.0.0.0         255.255.255.255 UH    0      0        0 vmbr0
136.243.79.209  0.0.0.0         255.255.255.255 UH    0      0        0 vmbr0
136.243.79.210  0.0.0.0         255.255.255.255 UH    0      0        0 vmbr0
136.243.79.221  0.0.0.0         255.255.255.255 UH    0      0        0 vmbr0

I can't post the results of route -n on the guest VM because I can't install net-tools because of my network issues.

Does anyone know where the problem might occur in my setup?

Edit:
I also allowed IPv4 forwarding on the Host system:
Code: 
[...]
# Uncomment the next line to enable packet forwarding for IPv4
net.ipv4.ip_forward=1

# Uncomment the next line to enable packet forwarding for IPv6
#  Enabling this option disables Stateless Address Autoconfiguration
#  based on Router Advertisements for this host
net.ipv6.conf.all.forwarding=1
net.ipv4.conf.all.proxy_arp = 1
[...]
 
Last edited:
I have restarted the host at least once after every 1-2 changes to the networking to be sure that everything loads correctly at startup.
 
Try and run these commands and restart the vps and not dedi

sysctl -w net.ipv6.conf.all.forwarding=1
sysctl -w net.ipv4.ip_forward=1

I've had a odd error with the network and turns out that these didn't stick
 
I just tried that, but it doesn't seem to do anything. I can ping the host but nothing outside.
I, unfortunately, can't trace the packages because none of the required packages is installed.
 
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