Broken pages and images in Internet Explorer with WinGate

[psiracusa]

Very often we lost some images and part of web pages when we're using WinGate proxy (last version). This problem does not appear when we're not using WinGate (a simple ip routing).
Our network topology is like this :

Workstations <-> Cisco router <-> WinGate Proxy <-> Cisco Router <-> Internet

The noticeable thing is that there's NAT between Workstations and the WinGate proxy.

Any idea to resolve this problem ?

Patrice

[jamesc]

1. If the images are not loading due to policies, then you will see authorisation errors in the System Messages tab of the GateKeeper.
GateKeeper --> View menu --> System Messages.

For Example, a policy is made only to allow connectivity to a domain named www.somedomain.com, but some images are coming from a different location, i.e. images.somedomain.com or advertising.anotherdomain.com


2. If it is not a policy problem, you can try creating a caching rule to not cache that website. An example is shown in the image below; replace prohire.com to the domain you are having problems with.

[psiracusa]

No authentication erros in WinGate system errors : we are not using this kind of policies so the problem is not due to domains that are allowed and others not.

Another strange problem : WinGate firewall is DISABLED but a lot of errors appear in GateKeeper firewall panel : "Checksum failure"

What does it mean ?

thanks

[jamesc]

--> Did you try to create a caching policy as detailed in my last post?

Another strange problem : WinGate firewall is DISABLED but a lot of errors appear in GateKeeper firewall panel : "Checksum failure"

--> Are you using NAT?
--> Can you try updating the drivers for your network card?




What does it mean ?

Reference: http://forums.qbik.com/viewtopic.php?t=4322

Basically it means that the packets were dropped due to having a bad checksum.

This can happen if the packet was corrupted in transit, or sent incorrectly, or in some cases where there may be an intermediate NDIS driver in your network stack that is messing with the checksums.

If received on the wire with a bad checksum, the rule is to drop the packet. We always did this before, but I figured we shouldn't drop packets without some notification, so I added the notification into 6.1

If there is some piece of software on your system that is breaking checksums, then that could cause good packets to be dropped. It is always possible there is some sort of exploit attempt being made as well.

WIngate behaviour changed a bit with 6.1 in regard to handling checksum failures - before 6.1 Wingate simply dropped the packets while in 6.1 it started reporting them - that's why it shows all these "Incorrect checksum" hits. If the number of dropped packets is low, there is nothing to worry about. If it becomes a stream of errors, then it is either a hardware fault somewhere on the line (interference) or it might indicate an attempt to attack the server.