Git SSH error: "Connect to host: Bad file number"

After having this problem myself, I found a solution that works for me:

Error message:

    ssh -v [email protected]
    OpenSSH_5.8p1, OpenSSL 1.0.0d 8 Feb 2011
    debug1: Connecting to github.com [207.97.227.239] port 22.
    debug1: connect to address 207.97.227.239 port 22: Connection timed out
    ssh: connect to host github.com port 22: Connection timed out
    ssh: connect to host github.com port 22: Bad file number

You will only see the bad file number message when on windows using the MINGGW shell. Linux users will just get Timed out.

Problem:

SSH is probably blocked on port 22. You can see this by typing

    $nmap -sS github.com -p 22
    Starting Nmap 5.35DC1 ( http://nmap.org ) at 2011-11-05 10:53 CET
    Nmap scan report for github.com (207.97.227.239)
    Host is up (0.10s latency).
    PORT   STATE    SERVICE
    22/tcp ***filtered*** ssh

    Nmap done: 1 IP address (1 host up) scanned in 2.63 seconds

As you can see the state is Filtered, which means something is blocking it. You can solve this by performing an SSH to port 443 (your firewall / isp will not block this). It is also important that you need to ssh to "ssh.github.com" instead of github.com. Otherwise, you will report to the webserver instead of the ssh server. Below are all the steps needed to solve this problem.

Solution:

(First of all make sure you generated your keys like explained on http://help.github.com/win-set-up-git/)

create file ~/.ssh/config (ssh config file located in your user directory. On windows probably %USERPROFILE%\.ssh\config

Paste the following code in it:

    Host github.com
    User git
    Hostname ssh.github.com
    PreferredAuthentications publickey
    IdentityFile ~/.ssh/id_rsa
    Port 443

Save the file.

Perform ssh like usual:

$ssh -T github.com 
    $Enter passphrase for key '.......... (you can smile now :))

Note that I do not have to supply the username or port number.

The key information is written in @Sam's answer but not really salient, so let's make it clear.

"Bad file number" is not informative, it's only a sign of running git's ssh on Windows.

The line which appears even without -v switch:

ssh: connect to host (some host or IP address) port 22: Bad file number

is actually irrelevant.

If you focus on it you'll waste your time as it is not a hint about what the actual problem is, just an effect of running git's ssh on Windows. It's not even a sign that the git or ssh install or configuration is wrong. Really, ignore it.

The very same command on Linux produced instead this message for me, which gave an actual hint about the problem:

ssh: connect to host (some host or IP address) port 22: Connection timed out

Actual solution: ignore "bad file number" and get more information

Focus on lines being added with -v on command line. In my case it was:

debug1: connect to address (some host or IP address) port 22: Attempt to connect timed out without establishing a connection

My problem was a typo in the IP address, but yours may be different.

Is this question about "bad file number", or about the many reasons why a connection could time out ?

If someone can prove that "bad file number" only appears when the actual reason is "connection time out" then it makes some sense to address why connection could time out.

Until that, "bad file number" is only a generic error message and this question is fully answered by saying "ignore it and look for other error messages".

EDIT: Qwertie mentioned that the error message is indeed generic, as it can happen on "Connection refused" also. This confirms the analysis.

Please don't clutter this question with general hints and answer, they have nothing to do with the actual topic (and title) of this question which is "Git SSH error: “Connect to host: Bad file number”". If using -v you have more informative message that deserve their own question, then open another question, then you can make a link to it.