For proxy with ImageSilo on Amazon, you can have the client try the following:
Add *.Amazonaws.com to your proxy/firewall whitelist.
If the above addresses the issue and they don’t want to use the *.Amazonaws.com to cover all options, then you can provide them the below options which are a bit more restrictive:
Here's the list of URL options from least restrictive and most flexible, to most restrictive and least flexible...
This is the broadest option, but will allow for them to access any bucket type/name in any US region we use...and as such, will allow for additions made in the future w/o them having to make any updates to their rules.
silo-us-*.s3*.amazonaws.com
These items will account for any bucket type/name in the regions we (currently) use. If we add new US regions, they would have to add new rules.
silo-us-*-useast1.s3.amazonaws.com
silo-us-*-uswest2.s3-us-west-2.amazonaws.com
These items are the most restrictive, and any changes/additions we make to bucket types and US regions in the future will need to be manually added.
silo-us-docs1-useast1.s3.amazonaws.com
silo-us-docs1-uswest2.s3-us-west-2.amazonaws.com