Problems with OpenBSD dhclient

[Eric Anderson]

Darren Pilgrim wrote:
> From: Eric Anderson
> 
>>Here's what I think would work well in most situations:
>>
>>  If another interface (B) is currently down, that has 
>>dhclient running 
>>on it, then when interface (A) comes up with a valid ip, it should 
>>remove the ip info from interface (B).
> 
> 
> This is a very bad idea.  Unless the interfaces have been bonded or
> configured as redundant for each other, they're independent by design.
> If I'm using the wired port to do any of the many useful things one can
> do with multiple interfaces (diagnostics, configuring new devices
> without loss of internet access, etc.), I don't want the unavoidable
> link-state changes on that interface to result in my wireless connection
> going down.

I think something was lost in the mix somewhere here.  What I said 
shouldn't cause your wireless connection to go down.  One of us is not 
understanding the other :)


>>If an interface (A) changes from down->up has conflicting IP 
>>information 
>>with an interface (B) that is down, that dhclient manages, it should 
>>remove the IP setup from interface (B), and set routes 
>>according to the 
>>newly upped interface.
>>
>>If an interface (A) changes from down->up, and there is another 
>>interface (B) that is up that dhclient manages, then 
>>configure interface 
>>(A) only if it will not conflict with the other interface's 
>>(B) network. 
>>  This could be an rc.conf option - to force newly brought up 
>>interfaces 
>>to override currently up interfaces.
> 
> 
> No.  Multiple interfaces with addresses in the same subnet (or even the
> same address) is a routing issue.  Dhclient is not the correct tool to
> solve routing issues.

Well, it is a routing issue, but it is one that dhclient needs to be 
able to gracefully deal with.   It should do *something* obviously, so 
what is it you propose for it to do?

> A dhclient program needs to do only one thing: negotiate a lease for the
> interface specified.

Ok - so if that's all it does, then what sets up the interfaces with the 
new lease?  What decides when to set up the interface and when not to? 
Are there any checks done, or does it blindly set up interfaces at will?

I think the question that needs to be answered here apparently is do we 
want FreeBSD to handle link change events in a default user-friendly 
manner without user interaction, or do we want it to just wait for the 
user to handle all events?

Eric




-- 
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Eric Anderson        Sr. Systems Administrator        Centaur Technology
A lost ounce of gold may be found, a lost moment of time never.
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