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"Forbidden" or "HTTP 403 - Access Forbidden" error message when trying to access a URL using InterScan Web Security Virtual Appliance (IWSVA) as a proxy

    • Updated:
    • 10 Jan 2017
    • Product/Version:
    • InterScan Web Security Virtual Appliance 6.0
    • InterScan Web Security Virtual Appliance 6.5
    • Platform:
    • N/A-N/A
Summary

In some cases, you receive a "Forbidden" or "HTTP 403 - Access Forbidden" message for a specific URL when IWSVA is set as the proxy.

 
The message may be different depending on the the web server reply.
Details
Public

This is because Content Cache is enabled in IWSVA. When using Content Cache, the outgoing HTTP request will add a "via" header that the web server does not support, and therefore it sends back the "Forbidden" message.

  1. Run a packet capture from IWSVA. To do this, go to Administration > Support > Network Packet Capturing tab > Select the correct network interface > Start Capturing > Reproduce the issue > Stop Capturing then download the packet capture.
  2. Enter the following in the Filter:

    ip.src == XXXXX

    Where XXXXX is the IP address of IWSVA.

  3. Look for the GET request from IWSVA to the website in question.
  4. Right click the entry and select Follow TCP stream.
  5. In the "Follow TCP stream" window, look for an entry containing the word "via"

    For example:

    Click image to enlarge

If you find the "via" entry and Content Cache is enabled (HTTP > Configuration > Content Cache), make the following changes:

  1. SSH to IWSVA.
  2. Do a backup of the following configuration file:

    cp /usr/iwss/ats/etc/trafficserver/records.config /usr/iwss/ats/etc/trafficserver/records.config.bak

  3. Edit the original configuration file and set the value of the string below to 0:

    vim /usr/iwss/ats/etc/trafficserver/records.config
    CONFIG proxy.config.http.insert_request_via_str INT 0 (Default value is 1)

  4. Save and exit.
  5. On the IWSVA web console, clear the content cache by going to HTTP > Configuration > Content Cache > Clear cache.

     
    Clearing a large cache may take a significant amount of time.
Premium
Internal
Rating:
Category:
Configure; Troubleshoot
Solution Id:
1116465
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