Does Firefox connect to 'ad.ca.doubleclick.net' by default??

[satyr]

I am curious why does Firefox connect to "ad.ca.doubleclick.net" by default (all of my four profiles, and I use them with "MOZ_NO_REMOTE" user env. variable so that I can run more than one instance/process at any time) as you can see in this image below, i.e. a screenshot of Process Explorer TCP/IP tab.



And what's even more interesting is that I block access to that server first in "hosts" file with "127.0.0.1 ad.ca.doubleclick.net" line, and secondly also with my DNSKong caching/filtering local DNS server program in the "named.txt" file (with simply one "doubleclick" line; I do however permit access to " ad.doubleclick.net" in the "pass.txt" because Ars Technica forum that I frequent advertises through it, and disabling it would result in banning me), which can be clearly visible (i.e. access denied) in these two screenshots of IE and Firefox below.





By the way, that tiny graphic in the last two screenshots is from eDexter, which is another program (beside same as "DNSKong") from Pyrenean website.

satyr

[satyr]

Well and I've just found out one even more strange thing: Firefox re-connects (i.e. a green colour in PE's TCP/IP tab) to "ad.ca.doubleclick.net" every few seconds (at least I guess so, I haven't observed it more closely) even if "Work Offline" check-box is checked ...

satyr

[James]

I am curious why does Firefox connect to "ad.ca.doubleclick.net" by default (all of my four profiles, and I use them with "MOZ_NO_REMOTE" user env. variable so that I can run more than one instance/process at any time) as you can see in this image below, i.e. a screenshot of Process Explorer TCP/IP tab.

MOZ_NO_REMOTE was for Firefox 1.5 at the time as one can use -no-remote now.

[Pike]

It's not connecting to "ad.ca.doubleclick.net", it's connecting to "127.0.0.1" but since you've mapped the two together in your hosts file, Process Explorer looks up the IP address and finds the doubleclick domain.

See here for more information about the connections established by Firefox:

http://kb.mozillazine.org/Connections_e ... _-_Firefox

[satyr]

It's not connecting to "ad.ca.doubleclick.net", it's connecting to "127.0.0.1" but since you've mapped the two together in your hosts file, Process Explorer looks up the IP address and finds the doubleclick domain.

Hey, thanks for the reply. But I don't understand why Firefox is connecting only to this particular host (i.e. "ad.ca.doubleclick.net") since I have many hostnames mapped to localhost IP, and not just the mentioned doubleclick one.

And also, isn't it that you map some hostname to 127.0.0.1 and not reverse, I mean for instance in this case, if I mapped "ad.ca.doubleclick.net" to 127.0.0.1, this doesn't mean that 127.0.0.1 is reverselly mapped to "ad.ca.doubleclick.net" (and all the other hostnames)?!!

satyr

[mrs260]

Wild guess here, but maybe "ad.ca.doubleclick.net" is the first listing in your hosts file? All the host file based ad-blocking advice I've seen has been careful to mention that you should leave an entry for "localhost" at the top.

[satyr]

Wild guess here, but maybe "ad.ca.doubleclick.net" is the first listing in your hosts file? All the host file based ad-blocking advice I've seen has been careful to mention that you should leave an entry for "localhost" at the top.

Ahhh thanks much for the suggestion, you mean something like "127.0.0.1 localhost", right??! And by the way, no, it's not listed first!!

satyr

[Pike]

Hey, thanks for the reply. But I don't understand why Firefox is connecting only to this particular host (i.e. "ad.ca.doubleclick.net") since I have many hostnames mapped to localhost IP, and not just the mentioned doubleclick one.

Firefox isn't connecting to ad.ca.doubleclick.net it's connecting to 127.0.0.1, Firefox knows nothing about ad.ca.doubleclick.net, it only appears to be connecting to that host because Process Explorer is looking up 127.0.0.1 and finding the entry in your hosts file.

And also, isn't it that you map some hostname to 127.0.0.1 and not reverse, I mean for instance in this case, if I mapped "ad.ca.doubleclick.net" to 127.0.0.1, this doesn't mean that 127.0.0.1 is reverselly mapped to "ad.ca.doubleclick.net" (and all the other hostnames)?!!

It depends on how the application does it, but some methods query the hosts file in the other direction too.

[satyr]

Wild guess here, but maybe "ad.ca.doubleclick.net" is the first listing in your hosts file? All the host file based ad-blocking advice I've seen has been careful to mention that you should leave an entry for "localhost" at the top.

You know that this actually did the trick (of course, only after a reboot), namely I've put the lines below to the beginning of my hosts file, and now PE shows for Firefox (and other such processes) that it's connecting to/from 127.0.0.1 (i.e. Local and Remote Address) even if "Resolve Addresses" is checked.

satyr