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I have just started playing around with AWS and I've been reading the docs as I go but I have run across a strange problem that I cannot explain and I was hoping someone experienced in AWS would be able to answer.

Certain websites return a 503 http response from my EC2 node, yet others do not. For instance: Canadian Company Capabilities returns a 503 via lynx and other tools yet Government Login does not.

Is one being blocked from outside of Canada or not? How can I diagnose the root cause of the 503?

EDIT I should mention I am using a standard CentOs, free tier ec2 instance. The rest of the pipeline is out of the box AWS free-tier as well.

EDIT 2 I have connected through a VPN in the states and it works fine as well which leads me to believe it's something I am missing with AWS.

gwnp
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  • Both websites are working for me? Also add more details how are the website hosted what are the web servers and language the website is build on etc. – Piyush Patil Aug 21 '16 at 18:54
  • It might be that your ISP is blocking those addresses, or; if you've just recently added those domains, then your system's DNS cache hasn't been updated. – hjpotter92 Aug 21 '16 at 18:57
  • I can connect to it from my house in Canada and via a VPN-tunnel in the states. The websites are not mine so I am not sure about the above hosting information, I just stumbled across them and was hoping someone knew why they do not work on AWS – gwnp Aug 21 '16 at 19:05

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How can I diagnose the root cause of the 503

You contact the site's administrator.

This won't be an AWS issue. AWS does not block, screen, scan, filter, modify, or otherwise manipulate Internet traffic that you initiate. It's possible for your own misconfiguration to block traffic entirely, but 503 is an HTTP error, which implies that you're making a connection to the distant end.

The exception to the above is outbound TCP port 25, which is not blocked but is very aggressively rate-limited unless you take the necessary steps to remove the block... but I mention this only for thoroughness; it of course would not be relevant to the issue at hand.

Michael - sqlbot
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