Lisa Muir writes:
I've been adding dns blacklists through the courier webadmin with
great results. Wanted to add lashback to the list, and found this in
their info:
if you wish to check whether 192.168.1.100 is listed in the UBL, you
would perform a DNS lookup on 100.1.168.192.ubl.unsubscore.com
Is this how the web configured DNS blacklists work or do they simply
They all work this way.
make a reverse DNS lookup on the IP address? I was hoping to migrate
the blacklist lookups to a localhost BIND and effectly use it as a
proxy for courier to make one single rdns lookup on, but if they all
operate like lashback, then thats not going to work with multiple
dnsbl's
Why not? It'll work just fine. Of course, it will get slow. Once you get
beyond 3-4 DNSBLs, the server will spend a noticeable amount of time waiting
for remote DNS queries to come back.
The usual solution is to make arrangements with your DNSBL's operators to
let your nameservers do zone transfers, rather than ad-hoc queries. This
will effectively keep your DNS lookups local, and each check essentially
translates to a rather fast database dip. You can't expect it to get faster
than that.
6 messages in net.sourceforge.lists.courier-usersRe: [courier-users] DNS lookup blacklist
