[CentOS] NetworkManager default route

[Gordon Messmer]

On 03/17/2016 12:04 PM, Sander Kuusemets wrote:
> Why is it so, that NetworkManager allows, and in several cases I've 
> had, defaults to setting default route to several interfaces at the 
> same time?

It does what the operators of the networks tell it to do.

> Had my fair share of problems with how 172.17.62.something interface 
> tries to ask for a DHCP lease from 193.something network.

Specifically why is that wrong?  If the interface is physically attached 
to broadcast domain where a DHCP server provides information for 
193.something, then presumably that is the information that the client 
should use.

> I know I could set never-default to the interfaces, but I shouldn't 
> have to do it to every machine I had.

Well, the way you would avoid configuring every client would be to offer 
consistent information from DHCP.

> Especially bad was the situation when I had two VLANs and a normal 
> ethernet interface, and dhclient tried to ask a lease for the ethernet 
> over the VLAN.

Do you mean tagged VLANs?  What you're describing shouldn't be 
possible.  If the client doesn't know about a tagged VLAN, it can't 
transmit a tagged packet containing a DHCP request.

If that's not what you're describing, the problem really isn't clear.