Popular Proxy Safe Search Bypass
While evaluating SecureComputing(WebWasher), Sophos, SafeSquid, DansGuardian and BlueCoat, all of which have the ability to rewrite a URL or forge your cookie for search engines so that they can enable "safe search" for most search engines, I figured out how to bypass all of them for this feature. While this will effectively bypass the "safe search" functions of the above proxies, it does not help you bypass keyword, blacklists or other content inspection mechanisms that will likely flag any of the links and block you there.
For google, the following string placed on the end of the search URL will do the trick for all 5 of them:
&safe=active&safe=off or &safe=vss&safe=off
You can even shorten it for most too &safe=&safe=off. Sohpos and BlueCoat (I didn't pay much attention to the rest) will actually rewrite your cookie as it's sent to enable safe search, but I suppose google looks to the URL for the final word on safe search. It might be that Sophos and BlueCoat only look for "&safe=" and ignore whats after it I'm not sure.
Sophos seems to miss Yahoo safe search completely... but for the others the bypass is very similar if not identical to
the google one above...
&vm=r&vm=i or &vm=&vm=i (you can use "p" in place of "i" also)
Live.com (MSN Search) is a little trickier, and not as easily fooled by the same tactics, and I have not found
a URL/Switch that allows you to turn off safe search, only turn it on...
&adlt=strict or &adlt=moderate or even demote
I don't think anyone uses M$ search anyways ;) But it was an interesting find. I can't remember which ones, but more than two out of the five were easily tricked by using a ccTLD (co.uk, .ie etc...) or using an IP address instead of the FQDN.