VDSL private subnet on WAN

Hi all,

I’ve got a VDSL Business Line with a /30 public IP Subnet for my use.
The provider uses a bit of a tricky configuration:
When you dial in with PPPoE you get a private 172.xx.xx.xx IP Address and also a default gateway. The provider static routes your public IPs to the private 172.xx you get. So now you can take your IP Addresses and bind them to interfaces and all works well.

The only issue is: I cannot make internet connections with the 172.xx IP, I have to use one of my public IPs. For example, NTP Service. In Cisco world I can do a “ntp source-interface” and select one of the interfaces where my public IPs are.

Is there any way to achieve this with vyos?

TL;DR: Default IP/Route does not go to the internet, how can I select source-interfaces for vyos-system?


Kind Regards,

depending on your physical topology you can assign your public IPs to ethernet interfaces or use a dummy interface. after that you configure NAT to use those public IPs

Note: You can even use sNAT/dNAT rules without assigning any address of public /30 range to VyOS interface.

Thanks for your replies!
This is currently what I’m doing. Assigning the IPs to dummy interfaces and using NAT.
The only question is: How can I get things like the NTP Service from vyos to use one of the dummy interfaces ip address? At the moment it tries to use the private ip from pppoe which doesn’t route to the internet and therefor NTP or DNS is not working.

Many thanks!

Kind regards,

Okay, so I found a solution for DNS: You can use the source-address parameter here.

This is not possible for NTP, there is no source-address parameter. Its not critical for me since I’m currently running in a VM anyway, but maybe a feature request …?

If you can’t set source, use a sNAT rule.
Filter on original source matching pppoe address , new address is one of your true WAN IPs.

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