I tried to use public key authentication on my new server, and I came across this problem.
$ ssh -v -i .ssh/server 192.168.1.100 OpenSSH_5.6p1, OpenSSL 0.9.8r 8 Feb 2011 debug1: Reading configuration data .ssh/config debug1: Applying options for * debug1: Reading configuration data /etc/ssh_config debug1: Applying options for * debug1: Connecting to 192.168.1.100 [192.168.1.100] port 22. debug1: Connection established. debug1: identity file .ssh/server type -1 debug1: identity file .ssh/server-cert type -1 debug1: Remote protocol version 2.0, remote software version OpenSSH_5.8p1 Debian-1ubuntu3 debug1: match: OpenSSH_5.8p1 Debian-1ubuntu3 pat OpenSSH* debug1: Enabling compatibility mode for protocol 2.0 debug1: Local version string SSH-2.0-OpenSSH_5.6 debug1: SSH2_MSG_KEXINIT sent debug1: SSH2_MSG_KEXINIT received debug1: kex: server->client aes128-ctr hmac-md5 none debug1: kex: client->server aes128-ctr 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 '192.168.1.100' is known and matches the RSA host key. debug1: Found key in .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: Roaming not allowed by server 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: .ssh/server debug1: read PEM private key done: type RSA debug1: Authentications that can continue: publickey,password debug1: Next authentication method: password
and then I have to input my password to get logged in.
But, if I already have one session connected to that server (which is connected by password), then the following connection uses key auth to avoid password input.
If there is no SSH connection already established, I can't connect without input password.
This is really weird to me, I checked the MD5 of
/usr/sbin/sshd between the new server and the other normal server, it's the same. Then I just copied the
/etc/ssh/sshd_config from the other normal server to the new server, and ran
service ssh restart. The problem still exists.
How am I supposed to fix this?