Can't connect to certain hosts on port 80

Question

I'm totally stumped by this so any suggestions would be great! My dev machine running OSX Mavericks, which works fine otherwise, can't connect to major sites like google, youtube and some CDNs (like stackexchange's CDN). The error I get from a

wget http://maps.google.com/ 

is

Connecting to maps.google.com|2607:f8b0:400a:804::100e|:80... connected.
HTTP request sent, awaiting response... No data received.

If I telnet to port 80 of stackexchange cdn and try a helo I get

telnet 141.101.114.59 80
Trying 141.101.114.59...
Connected to 141.101.114.59.
Escape character is '^]'.
helo
Connection closed by foreign host.

Another example:

telnet cdn.sstatic.net 80
Trying 2400:cb00:2048:1::be5d:f53a...
Connected to sstatic.net.cdn.cloudflare.net.
Escape character is '^]'.
GET /index.html
Connection closed by foreign host.

The same commands work perfectly if I try them from my other machines but I did notice the second example on a unix server returns a regular IP. This problem is consistent even when I change networks and seems specific to the port because I can connect to port 443 just fine on the same hosts. I also tried everything as a new user in case there were some user specific settings but no luck.

So is there some system specific setting in osx that would prevent some, but not all, port 80 traffic? Or should I just wipe the machine and start fresh?

Thanks so much!

Answer 1

If you are try to use telnet to send raw messages to a web server, you need to use actual raw HTTP, another reference , not the telnet or smtp commands since the webserver likely only speaks HTTP.

e.g., something like:

GET /index.htm HTTP/1.1 
host: www.example.com

Do you have any firewalls, proxies, etc in your path which may be refusing the traffic? Also, have you checked that your DNS is working? Other things to try is accessing the website directly by IP instead of host name.

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To troubleshoot your problem, you need to likely capture some traffic to see if it is being refused or if it's just timing out. You may be able to do this using some of the developer tools in your browser (e.g., Chrome's developer tools network panel) if their is a "network" monitor option. Otherwise, you can use a program like WireShark. This will give you more information on what is happening at the network level.