How to set up supplemental IP subnet

[tsajuk]

I have following IP network configuration from my provider (Hetzner):
x1.x2.x3.235 = IP address of the PVE host
x1.x2.x3.225 = IP address of the gateway

y1.y2.y3.32/29 = eight supplemental IP adresses which are routed from the gateway to the IP address of the server x1.x2.x3.235. to be used as IPs by the VMs

I simply can't find a way to enter this network configuration into the PVE network setup. Does someone have a hint?

 

[tog]

x.x.x.255 would be a broadcast IP unless your subnet mask is 255.255.254.0 or larger...

This is a tough question, basically you're asking your Proxmox VE box to also be a gateway router for this /29 you've been assigned. Hopefully tom or dietmar have a bright idea about how you might deal with that setup.

Perhaps if you had two ethernet interfaces in the system you could assign your /29 to the second ethernet adapter and that would be the interface you'd bridge your venets and veths to?

 

[tsajuk]

x.x.x.255 would be a broadcast IP unless your subnet mask is 255.255.254.0 or larger...

sorry I mistyped the last byte - corrected now.
I'm hopefully on the right way by doing:

• host: eth0 set to x1.x2.x3.235 mask 255.255.255.240 gw x1.x2.x3.225
• host: vmbr0 set to y1.y2.y3.38 mask 255.255.255.248 brigde ports none
• host: the VM's interface ( hopefully tap0 ) is bound to the vmbr0 bridge
• host: route add -host y1.y2.y3.33 dev vmbr0
• in VM: eth0 set to y1.y2.y3.33 mask 255.255.255.248 gw y1.y2.y3.38

from the VM I can now ping:

• y1.y2.y3.33 - o.k.
• y1.y2.y3.38 - o.k.
• x1.x2.x3.235 - o.k.
• x1.x2.x3.225 - fail

from the external internet i can ping:

• x1.x2.x3.235 - o.k.
• y1.y2.y3.38 - o.k.
• y1.y2.y3.33 - fail

where is the trick? the networks overlap on two nodes but still are disparate???

 

[dietmar]

You need to add a second route, something like:

http://www.proxmox.com/forum/showthread.php?t=841

Does you provider allow changing MAC addresses?

 

[dietmar]

Forget my last post, the setup you posted looks good.

Maybe you can debug using tcpdump (to see where packets gets lost).

- Dietmar

 

[dietmar]

Just a guess, but it looks like you need to enable proxy-arp somehow - will test that here on monday.

 

[dietmar]

Please try the following:

echo 1 > /proc/sys/net/ipv4/conf/eth0/proxy_arp

This enable proxy_arp on eth0 and enable external hosts to see your guests.

 

[dietmar]

Just updated our wiki - hope its more helful now.

http://pve.proxmox.com/wiki/Network_Model

 

[tsajuk]

Maybe you can debug using tcpdump (to see where packets gets lost).- Dietmar

Thanks to all. After installing Wireshark I found the hole in the setup. In fact, the problem jumps in my eyes if I read my original post again: my Host doesn't forward IP packets.

Despite a "net.ipv4.conf.default.forwarding=1" in the sysctl.conf the net/ipv4/ip_forward was still 0.
Now I've put

net.ipv4.conf.all.forwarding=1
net.ipv4.ip_forward = 1

inside as well - and it works.