Windows 7上的Git不会通过ssh进行连接，除非已经向服务器打开了另一个ssh连接

Question

I have this really weird problem with git on Windows 7. I've installed msysgit, generated the ssh keys, and added id_rsa.pub to authorized_keys on my Ubuntu machine. If I open the git bash shell and attempt to ssh into the server it prompts for a password. However I expect it to use the key and not prompt for a password. Now if I first open a ssh connection to the Ubuntu machine (via putty) and login, and then go back to the git bash shell the server accepts the connection with the key with no password.

Any ideas on what might be causing this connection weirdness?

Connect to server with no other ssh connections to server:

$ ssh -v jeremy@192.168.1.248
OpenSSH_4.6p1, OpenSSL 0.9.8e 23 Feb 2007
debug1: Reading configuration data /c/Users/Jeremy/.ssh/config
debug1: Connecting to 192.168.1.248 [192.168.1.248] port 22.
debug1: Connection established.
debug1: identity file /c/Users/Jeremy/.ssh/identity type -1
debug1: identity file /c/Users/Jeremy/.ssh/id_rsa type 1
debug1: identity file /c/Users/Jeremy/.ssh/id_dsa type -1
debug1: Remote protocol version 2.0, remote software version OpenSSH_5.1p1 Debian-6ubuntu2
debug1: match: OpenSSH_5.1p1 Debian-6ubuntu2 pat OpenSSH*
debug1: Enabling compatibility mode for protocol 2.0
debug1: Local version string SSH-2.0-OpenSSH_4.6
debug1: SSH2_MSG_KEXINIT sent
debug1: SSH2_MSG_KEXINIT received
debug1: kex: server->client aes128-cbc hmac-md5 none
debug1: kex: client->server aes128-cbc hmac-md5 none
debug1: SSH2_MSG_KEX_DH_GEX_REQUEST(1024<1024<8192) sent
debug1: expecting SSH2_MSG_KEX_DH_GEX_GROUP
debug1: SSH2_MSG_KEX_DH_GEX_INIT sent
debug1: expecting SSH2_MSG_KEX_DH_GEX_REPLY
debug1: Host '192.168.1.248' is known and matches the RSA host key.
debug1: Found key in /c/Users/Jeremy/.ssh/known_hosts:1
debug1: ssh_rsa_verify: signature correct
debug1: SSH2_MSG_NEWKEYS sent
debug1: expecting SSH2_MSG_NEWKEYS
debug1: SSH2_MSG_NEWKEYS received
debug1: SSH2_MSG_SERVICE_REQUEST sent
debug1: SSH2_MSG_SERVICE_ACCEPT received
debug1: Authentications that can continue: publickey,password
debug1: Next authentication method: publickey
debug1: Trying private key: /c/Users/Jeremy/.ssh/identity
debug1: Offering public key: /c/Users/Jeremy/.ssh/id_rsa
debug1: Authentications that can continue: publickey,password
debug1: Trying private key: /c/Users/Jeremy/.ssh/id_dsa
debug1: Next authentication method: password
jeremy@192.168.1.248's password:

Connect to server after opening ssh connection to server through putty:

$ ssh -v jeremy@192.168.1.248
OpenSSH_4.6p1, OpenSSL 0.9.8e 23 Feb 2007
debug1: Reading configuration data /c/Users/Jeremy/.ssh/config
debug1: Connecting to 192.168.1.248 [192.168.1.248] port 22.
debug1: Connection established.
debug1: identity file /c/Users/Jeremy/.ssh/identity type -1
debug1: identity file /c/Users/Jeremy/.ssh/id_rsa type 1
debug1: identity file /c/Users/Jeremy/.ssh/id_dsa type -1
debug1: Remote protocol version 2.0, remote software version OpenSSH_5.1p1 Debian-6ubuntu2
debug1: match: OpenSSH_5.1p1 Debian-6ubuntu2 pat OpenSSH*
debug1: Enabling compatibility mode for protocol 2.0
debug1: Local version string SSH-2.0-OpenSSH_4.6
debug1: SSH2_MSG_KEXINIT sent
debug1: SSH2_MSG_KEXINIT received
debug1: kex: server->client aes128-cbc hmac-md5 none
debug1: kex: client->server aes128-cbc hmac-md5 none
debug1: SSH2_MSG_KEX_DH_GEX_REQUEST(1024<1024<8192) sent
debug1: expecting SSH2_MSG_KEX_DH_GEX_GROUP
debug1: SSH2_MSG_KEX_DH_GEX_INIT sent
debug1: expecting SSH2_MSG_KEX_DH_GEX_REPLY
debug1: Host '192.168.1.248' is known and matches the RSA host key.
debug1: Found key in /c/Users/Jeremy/.ssh/known_hosts:1
debug1: ssh_rsa_verify: signature correct
debug1: SSH2_MSG_NEWKEYS sent
debug1: expecting SSH2_MSG_NEWKEYS
debug1: SSH2_MSG_NEWKEYS received
debug1: SSH2_MSG_SERVICE_REQUEST sent
debug1: SSH2_MSG_SERVICE_ACCEPT received
debug1: Authentications that can continue: publickey,password
debug1: Next authentication method: publickey
debug1: Trying private key: /c/Users/Jeremy/.ssh/identity
debug1: Offering public key: /c/Users/Jeremy/.ssh/id_rsa
debug1: Server accepts key: pkalg ssh-rsa blen 277
debug1: read PEM private key done: type RSA
debug1: Authentication succeeded (publickey).
debug1: channel 0: new [client-session]
debug1: Entering interactive session.
Linux curious 2.6.31-23-generic #74-Ubuntu SMP Mon Feb 28 22:20:11 UTC 2011 x86_
64

To access official Ubuntu documentation, please visit:
http://help.ubuntu.com/

Answer 1

I ran into a similar problem with just trying to ssh into my server, not git related. The actual issue was that my home directory on the server is encrypted. So unless the user is already logged in, the encrypted directory with the authorized_keys file is not mounted and thus not accessible by sshd. If the user already has a session open, the directory is mounted and ssh behaves as expected.

Here is the official Ubuntu help for this situation: https://help.ubuntu.com/community/SSH/OpenSSH/Keys#Troubleshooting

Here is the solution I used: https://bugs.launchpad.net/ubuntu/+source/openssh/+bug/362427/comments/12

And I got to both of these from this thread: https://superuser.com/questions/61057/ssh-with-authorized-keys-to-an-ubuntu-system-with-encrypted-homedir

Answer 2

My immediate suspicion is that it's looking for an authentication agent, and failing to find one, then failing to run ssh-askpass to unlock your private key for some reason. But if you start Putty, it starts the agent and sets it up properly, then the command line ssh can use it to get your private key.