Firewall Wizards mailing list archives
Re: Blocking Google Talk
From: "Julian M D" <julianmd () gmail com>
Date: Thu, 15 Jun 2006 15:04:19 -0400
Hey Mike, Try this on your ISA: It's possible to block Google Talk by : ==> URL blacklists : a.. talk.google.com:443 b.. talk.google.com:5222 c.. desktop.google.com/download/googletalk/google-talk-versioncheck.txt? ==> By signatures (For more information, see HTTP Filtering in ISA Server 2004 ) 2 User Agents : a.. Google Talk b.. Mozilla/4.0 (compatible; Win32) ==> By The Firewall Client Setting Dialog Box: Add new application entry setting Or process name "GoogleTalk.exe", use the "disable" key and Select the value 1 from the value list to block the application On 6/15/06, Mike Powell <mikep () dri-eaz com> wrote:
Does anyone have any ideas for blocking Google's new Google Talk client without blocking the Google web site? The IP addresses that the Talk client uses are the same addresses that resolve for Google. Even more difficult, Google doesn't have reverse (PTR) records to be able to usefully filter traffic to raw IP addresses. Even if they did, since the addresses are the same as for Google's web traffic (see above), blocking addresses used by the Talk client would break access to the Google website. Also, even though the documentation on the Google Talk web site states that the Google Talk client uses port 5222 (which we are successfully blocking), it seems to work just fine even if port 5222 is blocked and the only access is port 443(SSL). I know that it is working this way because I have tracked this in the logs, and it tries to connect on 5222, but also makes connections on 443 and then just keeps on going like there was no problem at all. We filter our internet-bound traffic through Microsoft's ISA 2004, and it is protocol-aware for http (port 80 and 443) traffic, so I can't think of a way to block the port 443 traffic as it appears to go through the ISA server as a valid SSL connection, just like someone browsing an SSL website. I'm really stuck on this. We only allow web access on ports 80 and 443 by corporate policy, yet a ton of our people are using this software. Help! _______________________________________________ firewall-wizards mailing list firewall-wizards () listserv icsalabs com https://listserv.icsalabs.com/mailman/listinfo/firewall-wizards
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Current thread:
- Blocking Google Talk Mike Powell (Jun 15)
- Re: Blocking Google Talk Julian M D (Jun 15)
- Re: Blocking Google Talk Kevin (Jun 15)
- Re: Blocking Google Talk Paul D. Robertson (Jun 19)
- Re: Blocking Google Talk Phil Trainor (Jun 19)
- Re: Blocking Google Talk ArkanoiD (Jun 20)
- Re: Blocking Google Talk Phil Trainor (Jun 20)
- Re: Blocking Google Talk Phil Trainor (Jun 19)
- Re: Blocking Google Talk Frank Knobbe (Jun 19)
- <Possible follow-ups>
- Re: Blocking Google Talk Paul D. Robertson (Jun 19)
- Re: Blocking Google Talk Frank Knobbe (Jun 19)
- Re: Blocking Google Talk R. DuFresne (Jun 20)
- Re: Blocking Google Talk Devdas Bhagat (Jun 20)
- Re: Blocking Google Talk Frank Knobbe (Jun 19)