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belvincent
Level 9

Weird behavior with proxy DIRECT and no proxy setting in Internet Explorer

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Hi,

We have a weird issue.

We have some sites that are altered when modifying the proxy settings in Internet Explorer.

We have MCP installed on computers to intercept all traffic to ports 80 and 443.

When unchecking all proxy settings, the following sites are fine.

When setting a proxy pac file returning DIRECT (so the same as no proxy), the sites are broken (altered or messed up).

With MCP, it should be the exact same behavior. You can test it easily of you have MCP.

Some samples sites:

http://www.lanacion.com.ar

http://www.cronica.com.ar

This behavior is occurring only on IE 10 and 11.

What could be the issue?

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belvincent
Level 9

Re: Weird behavior with proxy DIRECT and no proxy setting in Internet Explorer

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Sorry for the delay in my answer, we were investigating this tricky issue with the support.

In a nutshell, we had two issues:

- Internet Explorer "compatibility mode" is activated for all sites (external and internal) when proxy pac file returns direct, because the pac file server is on the intranet it seems. This breaks many sites designs. See:

https://connect.microsoft.com/IE/feedback/details/911520/websites-are-displayed-in-compatibility-mod...

- MCP and the browser with a proxy pac file returning DIRECT cannot settle peacefully who is handling the socket. Basically we have to choose between (using MCP and no proxy) OR (no MCP and a pac file returning explicit proxies).

I hope this information will be helpful for people designing their solutions around MCP for intercepting traffic all the time (internally and externally): Think twice!

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2 Replies
McAfee Employee

Re: Weird behavior with proxy DIRECT and no proxy setting in Internet Explorer

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Hi Vincent,

What did you see in the rule trace when reproducing this behavior?

If you have MCP installed as well as using MWG via proxy pac, the traffic you have bypassed in the proxy pac should be picked up by MCP (assuming its always redirecting).

If MCP is not "always redirecting" I would guess that the pages are not being sent to MWG and the content is blocked somehow.

Best Regards,

Jon

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belvincent
Level 9

Re: Weird behavior with proxy DIRECT and no proxy setting in Internet Explorer

Jump to solution

Sorry for the delay in my answer, we were investigating this tricky issue with the support.

In a nutshell, we had two issues:

- Internet Explorer "compatibility mode" is activated for all sites (external and internal) when proxy pac file returns direct, because the pac file server is on the intranet it seems. This breaks many sites designs. See:

https://connect.microsoft.com/IE/feedback/details/911520/websites-are-displayed-in-compatibility-mod...

- MCP and the browser with a proxy pac file returning DIRECT cannot settle peacefully who is handling the socket. Basically we have to choose between (using MCP and no proxy) OR (no MCP and a pac file returning explicit proxies).

I hope this information will be helpful for people designing their solutions around MCP for intercepting traffic all the time (internally and externally): Think twice!

0 Kudos