[Mimedefang] validating 'possibly forged' helo IP's?

[James Ebright]

Yeah, that is exactly what you have to do if you need to delegate the IP 
space as the ISP... I was also speaking about generating the relevant 
zone file containing the PTR records (the in.addr-arpa records) and we 
solved the classless delegation issue by simply requiring customers that 
want more than a single static IP address to complete ARIN forms to 
justify their use and need (since we have to do the same if we want more 
space ourselves!) and there is no space on our forms to select something 
arbitrary like.. 7 IPs hehe. I have no issues doing classless routing... 
but IP delegation is so much simpler all around if kept classfull. (and 
honestly, you can assign a customer a /29 and a /32 and give them 7 
usable addresses if they absolutely require only 7 IPs, so it is easy to 
play with).

In either case, you still need to generate your in.addr-arpa zones... 
and that is what I was referring to. :-)

Jim


Kenneth Porter wrote:

> --On Saturday, January 14, 2006 9:41 PM -0500 James Ebright 
> <jebright at esisnet.com> wrote:
>
>> It is trivial to setup PTR records for any size of IP space, you are
>> talking about less than 20 lines of shell code for a fairly complex
>> setup, can do it in one typed in for loop if you want.... so there 
>> really
>> is no excuse to not have any PTR records at all.
>
>
> There's macro syntax in BIND for doing exactly this, and it's what's 
> commonly used by the ISP to create the delegation for blocks that 
> don't fall on subnet boundaries (AKA "classless delegation"). Look for 
> "$GENERATE".
>
> Here's one approach:
>
> <http://homepages.tesco.net/~J.deBoynePollard/FGA/
> avoid-rfc-2317-delegation.html>
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