Permissions are set correctly on the server (chibi). If I do not have an existing ssh session open to the server, then all new sessions require a password. However if there's already one open, additional ssh sessions authenticate with pubkey correctly.
My $home is on an SD card. I moved authorized_keys to / and linked it, but that didn't resolve the issue.
No sessions open:
ting@core[0][09:11:32]:~$ ssh-add -L
ssh-rsa AAAAB3NzaC1yc2EAAAADAQABAAABAQDXRYefDRi18Qtlkfmt/qK5dbzMk5ajMgIv4+jUyWTtL1detZAs/hoIKocqBib5ul+/snrGiFbYV1JQiiLaidXNwe1nsNCk6UMagrRaCkPxyEqiygh9Ha5pf7anVdx2sLwdSXU42qKOgmVAHolpQfZQ4r/XItmR8fbDzNgkYeT+yEpm9b69wSl2d3xWPMd+EnqiqXuUoXISvMxDXIsC8I4qff6ms4JMX1S6HxBnVUKg/4DgJ7x07m4cM6RbXvGXNy2KBMhHoy45V/lPlf8pey+Af0Zxyw+na3mlG2WmAyOCnwXKJ/9TqLpYiCUHhTR4wgmgZpLWpSyyHYZhGP951ozP /home/ting/.ssh/id_rsa
ting@core[0][09:12:35]:~$ ssh -v chibi
OpenSSH_5.5p1 Debian-4ubuntu5, OpenSSL 0.9.8o 01 Jun 2010
debug1: Reading configuration data /etc/ssh/ssh_config
debug1: Applying options for *
debug1: Connecting to chibi [192.168.1.2] port 22.
debug1: Connection established.
debug1: identity file /home/ting/.ssh/id_rsa type 1
debug1: Checking blacklist file /usr/share/ssh/blacklist.RSA-2048
debug1: Checking blacklist file /etc/ssh/blacklist.RSA-2048
debug1: identity file /home/ting/.ssh/id_rsa-cert type -1
debug1: identity file /home/ting/.ssh/id_dsa type -1
debug1: identity file /home/ting/.ssh/id_dsa-cert type -1
debug1: Remote protocol version 2.0, remote software version OpenSSH_5.5p1 Debian-4ubuntu5
debug1: match: OpenSSH_5.5p1 Debian-4ubuntu5 pat OpenSSH*
debug1: Enabling compatibility mode for protocol 2.0
debug1: Local version string SSH-2.0-OpenSSH_5.5p1 Debian-4ubuntu5
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 'chibi' is known and matches the RSA host key.
debug1: Found key in /home/ting/.ssh/known_hosts:37
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: Offering public key: /home/ting/.ssh/id_rsa
debug1: Authentications that can continue: publickey,password
debug1: Trying private key: /home/ting/.ssh/id_dsa
debug1: Next authentication method: password
ting@chibi's password:
One session already connected, opening second session:
ting@core[0][09:14:14]:~$ ssh-add -L
ssh-rsa AAAAB3NzaC1yc2EAAAADAQABAAABAQDXRYefDRi18Qtlkfmt/qK5dbzMk5ajMgIv4+jUyWTtL1detZAs/hoIKocqBib5ul+/snrGiFbYV1JQiiLaidXNwe1nsNCk6UMagrRaCkPxyEqiygh9Ha5pf7anVdx2sLwdSXU42qKOgmVAHolpQfZQ4r/XItmR8fbDzNgkYeT+yEpm9b69wSl2d3xWPMd+EnqiqXuUoXISvMxDXIsC8I4qff6ms4JMX1S6HxBnVUKg/4DgJ7x07m4cM6RbXvGXNy2KBMhHoy45V/lPlf8pey+Af0Zxyw+na3mlG2WmAyOCnwXKJ/9TqLpYiCUHhTR4wgmgZpLWpSyyHYZhGP951ozP /home/ting/.ssh/id_rsa
ting@core[0][09:14:17]:~$ ssh -v chibi
OpenSSH_5.5p1 Debian-4ubuntu5, OpenSSL 0.9.8o 01 Jun 2010
debug1: Reading configuration data /etc/ssh/ssh_config
debug1: Applying options for *
debug1: Connecting to chibi [192.168.1.2] port 22.
debug1: Connection established.
debug1: identity file /home/ting/.ssh/id_rsa type 1
debug1: Checking blacklist file /usr/share/ssh/blacklist.RSA-2048
debug1: Checking blacklist file /etc/ssh/blacklist.RSA-2048
debug1: identity file /home/ting/.ssh/id_rsa-cert type -1
debug1: identity file /home/ting/.ssh/id_dsa type -1
debug1: identity file /home/ting/.ssh/id_dsa-cert type -1
debug1: Remote protocol version 2.0, remote software version OpenSSH_5.5p1 Debian-4ubuntu5
debug1: match: OpenSSH_5.5p1 Debian-4ubuntu5 pat OpenSSH*
debug1: Enabling compatibility mode for protocol 2.0
debug1: Local version string SSH-2.0-OpenSSH_5.5p1 Debian-4ubuntu5
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 'chibi' is known and matches the RSA host key.
debug1: Found key in /home/ting/.ssh/known_hosts:37
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: Offering public key: /home/ting/.ssh/id_rsa
debug1: Server accepts key: pkalg ssh-rsa blen 279
debug1: Authentication succeeded (publickey).
debug1: channel 0: new [client-session]
debug1: Requesting no-more-sessions@openssh.com
debug1: Entering interactive session.
debug1: Sending environment.
debug1: Sending env LANG = en_US.utf8
.bashrc executed.
.bash_aliases executed.
ting@chibi[0][14:14:41]:~$
Diff between the two sessions:
ting@core[0][09:20:47]:~$ diff ssh1.txt ssh2.txt
36,39c36,37
< debug1: Authentications that can continue: publickey,password
< debug1: Trying private key: /home/ting/.ssh/id_dsa
< debug1: Next authentication method: password
< debug1: Authentication succeeded (password).
---
> debug1: Server accepts key: pkalg ssh-rsa blen 279
> debug1: Authentication succeeded (publickey).
53,54c51,52
< Transferred: sent 2216, received 8360 bytes, in 11.2 seconds
< Bytes per second: sent 198.2, received 747.7
---
> Transferred: sent 2712, received 7464 bytes, in 9.1 seconds
> Bytes per second: sent 298.4, received 821.3
File permissions:
drwx------ 2 ting ting 4.0K 2011-03-30 14:00 .ssh/
-rw------- 1 ting ting 404 2011-03-30 14:00 authorized_keys
-rw------- 1 ting ting 132 2011-03-23 02:47 environment
-rw-r--r-- 1 ting ting 4.4K 2011-03-25 11:59 known_hosts
ting@chibi[0][23:57:13]:~/.ssh$
Best Answer
It seems your home directory or the place where your keys are, is encrypted. The first login mounts and decrypts the directory letting the ssh daemon use the keyfile.
Solution for that is to move the "authorized_keys"-file to a device where it is not encrypted by default.
After that you have to point the ssh daemon to that place. The following configuration option is used for that.
AuthorizedKeysFile Specifies the file that contains the public keys that can be used for user authentication. AuthorizedKeysFile may contain tokens of the form %T which are substituted during connection set-up. The following tokens are defined: %% is replaced by a literal '%', %h is replaced by the home directory of the user being authenticated and %u is replaced by the username of that user. After expansion, AuthorizedKeysFile is taken to be an absolute path or one relative to the user's home directory. The default is “.ssh/authorized_keys”.
Maybe like this