[I have posted the same issue on Ubuntu forums: http://ubuntuforums.org/showthread.php?t=2145713 . I am repeating it here to see if I can find an answer here.]
I installed Ubuntu 13.04 recently, and found that I can't connect to many sites, including Github, using Firefox(21.0) and Chrome(26.0.1410.63). I can visit all these sites on Windows, in all browsers.
Firefox continues to load the site, but doesn't show any contents. Chrome gives an error after a while:
Error 7 (net::ERR_TIMED_OUT): The operation timed out.
Some websites are loaded partially.
Some other sites with this issue: bitbucket(works on Chrome but not in Firefox), yahoo mail, 500px (partially loaded), images served from pcdn.500px.com are not loaded.
I also can't clone (git clone) github repositories: I get "error: operation timed out". I can clone bitbucket repos.
In addition I noticed the following "SSL" issue while using "pip" to install Python packages; the packages do get installed. I am including this in here in case it is related to the above issue:
$ pip install ipython Downloading/unpacking ipython Could not fetch URL https://github.com/ipython/ipython/downloads (from https://pypi.python.org/simple/ipython/): There was a problem confirming the ssl certificate: <urlopen error _ssl.c:489: The handshake operation timed out> Will skip URL https://github.com/ipython/ipython/downloads when looking for download links for ipython Downloading ipython-0.13.2.tar.gz (6.0MB): 6.0MB downloaded Running setup.py egg_info for package ipython Installing collected packages: ipython Running setup.py install for ipython Installing ipcontroller script to /home/phn/.virtualenvs/default2.7/bin Installing iptest script to /home/phn/.virtualenvs/default2.7/bin Installing ipcluster script to /home/phn/.virtualenvs/default2.7/bin Installing ipython script to /home/phn/.virtualenvs/default2.7/bin Installing pycolor script to /home/phn/.virtualenvs/default2.7/bin Installing iplogger script to /home/phn/.virtualenvs/default2.7/bin Installing irunner script to /home/phn/.virtualenvs/default2.7/bin Installing ipengine script to /home/phn/.virtualenvs/default2.7/bin Successfully installed ipython Cleaning up...
Note that I have none of these issues in Windows.
[Edit: May 17 2013]
Output from running curl on github:
[phn@phn ~ ] $ curl -I http://github.com HTTP/1.1 301 Moved Permanently Server: GitHub.com Date: Fri, 17 May 2013 03:33:08 GMT Content-Type: text/html Content-Length: 178 Connection: close Location: https://github.com/ Vary: Accept-Encoding [phn@phn ~ ] $ curl -I https://github.com curl: (35) Unknown SSL protocol error in connection to github.com:443
I hope someone can help me fix this.