Re: google search threshold

[Philip Lavine via NANOG <nanog () nanog org>]

I have about 2000 users behind a single NAT. I have been looking at netflow, URL filter logs, IDS logs, etc. The 
traffic seems to be legit. 

I am going to move more users to IPv6 and divide some of the subnets into different NATS and see if that alleviates the 
traffic load.
Thanks for the advice.
-Philip


      From: Damian Menscher <damian () google com>
 To: Philip Lavine <source_route () yahoo com> 
Cc: "nanog () nanog org" <nanog () nanog org>
 Sent: Friday, February 26, 2016 6:05 PM
 Subject: Re: google search threshold
   
On Fri, Feb 26, 2016 at 3:01 PM, Philip Lavine via NANOG <nanog () nanog org> wrote:

Does anybody know what the threshold for google searches is before you get the captcha?I  am trying to decide if I need 
to break up the overload NAT to a pool.


There isn't a threshold -- if you send automated searches from an IP, then it gets blocked (for a while).

So... this comes down to how much you trust your machines/users.  If you're a company with managed systems, then you 
can have thousands of users share the same IP without problems.  But if you're an ISP, you'll likely run into problems 
much earlier (since users like their malware).
Some tips:   - if you do NAT: try to partition users into pools so one abusive user can't get all your external IPs 
blocked  - if you have a proxy: make sure it inserts the X-Forwarded-For header, and is restricted to your own users  - 
if you're an ISP: IPv6 will allow each user to have their own /64, which avoids shared-fate from abusive ones
Damian (responsible for DDoS defense)-- Damian Menscher :: Security Reliability Engineer :: Google :: AS15169