Connection timeout when accessing Github [closed]

The solution:

after a long thread with Github support, they said it was a server side configuration related to a tentative of avoid DDOS attack that has affected some users, like me. After some adjustments in the Github server everything back to normal and works very fine again!

Thanks very much for Github support team, they were very transparent and helpful.

Quote from the long email thread:

Hi Felipe -

We've been experiencing intermittent DDoS attacks over the last several weeks, and an unfortunate side-effect of some of the preventative measures we've put in place is strange side-effects like this. We believe the problem here was that some of our DDoS protection was mis-configured. We're working with out network provider to tune the DDoS protection to not drop other traffic like this with the highest priority. Sorry again for the repeated problems here!

Jesse GitHub Ops

Googling around for your error message turns up some stuff about the MTU size.

If possible, I suggest you try a different network/ISP just to confirm it's only happening on that particular network.

Then, you could try changing the MTU (you could for instance see what Windows has for MTU and set Ubuntu's to that; by default it's 1500 on Ubuntu).

Here's how to change MTUs: http://ubuntuforums.org/showthread.php?t=1887063.

I suggest you first check on a different network and only then try to change the MTU. It's not something that needs to be done commonly so if changing networks helps, I'd say it's some weird issue with the network, to which Windows is somehow impervious.

I could help you diagnose it, if you disable all network applications apart from your application (git client in this case) to minimize the network noise and use tcpdump/wireshark to capture the traffic sent and received when you experience problems.

Make sure to start capturing before you run the command that's having trouble connecting.

Install both programs with:

sudo apt-get install wireshark tcpdump

and then run

sudo tcpdump -i wlan0 -o dump.pcap -s 1500

to start capturing before testing.

It would be helpful if you capture the traffic during one session that fails and upload the resulting dump.pcap somewhere where I could download it.

If you are not behind proxy then ignore this comment.

I am behind proxy at work and had to configure git to reach through it. Before that I had timeouts for github on Ubuntu machine while Windows machines worked fine.

So if you are behind proxy, then open your ~/.gitconfig file and add these lines:

[http]
    proxy = http://192.168.219.2:8080
[https]
    proxy = https://192.168.219.2:8080

Of course replace IP and port numbers with yours. Hope this helps