Smoothwall firewall seems to be preventing "large" uploads

Question

One of our customers has a Smoothwall firewall at the edge of their network. External users should be able to use a mobile app to upload images. The images are sent as base64 encoded strings in a JSON packet. However, the Smoothwall firewall seems to be stopping uploads after about 350kB have been tranmitted. I have performed various tests and it does not seem to be related to transmission time, i.e. the connection is not timing out.

According to Smoothwall documentation, there should be "File upload policy" settings within the Advanced Web Proxy settings, but there is no Advanced button / menu.

Any ideas what may be causing this? Is there anything we can do from the command line to find out if there is a file upload policy?

Answer 1

Sorry for the long delay in response here...

Are we talking about Smoothwall Express or our commercial offering?

If it's the latter then there are a number of things you can check/test.

Upload/Download limits can be modified under "Web proxy » Web proxy » Settings - Advanced - Web filter options" with options of [Allow unlimited uploads], [Block all uploads], and [Restrict upload size to X Kbytes]

As this appears to be sent as JSON, it may appear as a POST and not be seen as an upload, therefore message Censor (our outbound content filtering engine) may be blocking based on a random word within the Base64 encoded string (unlikely but still). You can check if Message Censor is enabled under "Guardian » Web filter » Outgoing".

Is there some other filtering policy being applied? You can add your IP address to "Source Exceptions" under "Guardian » Web filter » Outgoing" and then set your proxy to smoothwallip:801

With it being a mobile app, authentication or lack of SNI may be the problem here. You can add the domain to a new user defined category "Guardian » Policy objects » Categories" then make sure auth is not required at "Web proxy » Authentication » Exceptions". You may need to create a new policy for this new category with a whitelist action at "Guardian » Web filter » Policy wizard", be sure to drag it above any Quota, Block or Soft Block policies in the Web Filter Policy table.