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RSS Feed Reader - Error: Unable to download a feed from host

Thomas Hampel
 18 December 2014

Some time ago a user started to claim his Notes Sidebar would no longer display latest RSS news feeds.
Asking for details we checked functionality by subscribing to a new feed....which did not work either. The Notes client was throwing an error:

Image:RSS Feed Reader - Error: Unable to download a feed from host

Analysis:

At first one might think this is caused by the RSS feed itself, but since I'm a subscriber of the same feed I knew the root cause must be something different.

Within the corporate network Notes clients must be configured to use an HTTP proxy in order to access the internet, testing revealed outside of the customers network it is working fine when HTTP Proxy settings are disabled,

Feed reader components itself are running on the latest version, so
Michael Urspringer's hint (= SPR # IFAY7CTHAR ) seems not to apply
Image:RSS Feed Reader - Error: Unable to download a feed from host

Opening a PMR was followed with the usual request for logs and a
Wireshark network trace.
After some investigation and
discussions it turned out the network team changed some settings on the HTTP proxy server to block all HTTP traffic from web browsers where the user agent string includes "Windows NT 5.1" (which is Windows XP) because WinXP being out of support.

Wireshark showed the default setting for the feed reader in Notes 9.0.1 is user agent="Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 5.1; .NET CLR 1.1.4322; .NET CLR 2.0.50727; .NET CLR 3.0.4506.2152; .NET CLR 3.5.30729)"

...but how can you change this default??


A small hint can be found in the release notes of a previous
Notes client (8.5.2FP1) fix list
Take a closer look to SPR# MWER88NFWT which outlines the settings required for modifying the useragent.:


"Added an option to allow customers to override the "User Agent" value for Notes Client Feedreader. By default, Feed Reader authenticates itself as "MSIE 7.0" even on Linux and Mac.  
Customers can optionally add the following 2 lines to the /framework/rcp/plugin_customization.ini:

com.ibm.rcp.feedreader.providers/network.useragent.override=true

com.ibm.rcp.feedreader.providers/network.useragent=CUSTOMER SPECIFIED VALUE (<-replace CUSTOMER SPECIFIED VALUE with the value of your choosing)"



Solution:
  • Change the useragent string of the feed reader to anything else. (You can find a long list of user agents to choose from as part of a Firefox Plugin.)
    Modify the file /framework/rcp/plugin_customization.ini and add the following lines for testing
    com.ibm.rcp.feedreader.providers/network.useragent.override=true
    com.ibm.rcp.feedreader.providers/network.useragent=Mozilla/5.0 (Windows NT 6.1; Win64; x64; rv:25.0) Gecko/20100101 Firefox/25.0
  • After successful testing, deploy this parameter to all users by using Desktop Policies / Managed Settings:
    Image:RSS Feed Reader - Error: Unable to download a feed from host

Conclusion:

The HTTP proxy was configured according to
RFC 3314 but mistakenly assuming WinXP in a useragent string is evil
....and of course...
whatever is wrong, it must have been the network guy!
Tagged with: Administration Error Notes
Comments

1.) Untitled

Mr.T http:// 21.04.2015 11:44:54

Just posting to say THANK YOU. You saved me from spending a lot of time trying to figure out the problem. =)

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