How does DHCPD determine what IP address to assign and...

Ryan McCain Ryan.McCain at
Mon Jan 7 16:31:46 UTC 2008

>>> On Fri, Jan 4, 2008 at  5:27 PM, in message
<a06240804c3a46e2f798d at>, Simon Hobson
<dhcp1 at> wrote: 
> Ryan McCain wrote:
>>As far as you know, unless we upgrade to v4.x, there is no way we 
>>can accomplish this?
> You can do it, but it's much harder !
> The expression you already have should do it - we don't know why it 
> doesn't as we don't have enough information (you've been given some 
> suggestions on how to debug it). But essentially, as things currently 
> stand you have to cater for each possible format (ie 1, 2, or 3 
> digits after the "Async") by testing for multiple expressions.
> With version 4 and regex support you can just match for a regex along 
> the lines of "^[0-9.]+Async[0-9]+$" which means (if I've got it right 
> !) "At the start of the string, any sequence of one or more of the 
> characters zero through nine plus the point, followed by the 
> characters 'Async', followed by 1 or more characters zero through 
> nine, at the end of the string"
> ^ = match the start of the string
> [0-9.] = any one character from the set 0 to 9, or '.', might have to 
> be [0-9\.] to 'escape' the special meaning of '.'
> + = match one or more occurances of the previous part
> Async = the literal characters "Async"
> [0-9] = any of the characters 0 to 9
> + = match one or more of them
> $ = match the end of the string
> It's best to be as specific as practical, a regex of ".*Async.*" 
> means "Any sequence of zero or more occurances of any character, 
> followed by Async, followed by zero or more occurances of any 
> character" would probably match clients you didn't want it to - 
> specifically ANY string containing Async anywhere within it.

That answers all of my questions.  I'll start with the debugging/sniffing.

Thanks for your help...

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