A autenticação de pubkey SSH funciona somente se outra sessão já estiver aberta

Question

As permissões estão definidas corretamente no servidor (chibi). Se eu não tiver uma sessão ssh existente aberta ao servidor, todas as novas sessões exigirão uma senha. No entanto, se já existir uma sessão ssh adicional, autentique-a com o pubkey corretamente.

Minha conta $ está em um cartão SD. Mudei o authorized_keys para / e o vinculei, mas isso não resolveu o problema.

Nenhuma sessão aberta:

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: 

Uma sessão já está conectada, abrindo a segunda sessão:

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 [email protected]
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]:~$ 

Diferença entre as duas sessões:

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

Permissões de arquivo:

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$

    

Answer 1

Parece que o seu diretório pessoal ou o local onde suas chaves estão são criptografados. O primeiro login monta e descriptografa o diretório, permitindo que o daemon ssh use o arquivo de chaves.

A solução para isso é mover o arquivo "authorized_keys" para um dispositivo em que ele não é criptografado por padrão.

Depois disso, você deve apontar o daemon ssh para aquele lugar. A seguinte opção de configuração é usada para isso.

AuthorizedKeysFile Especifica o arquivo que contém as chaves públicas que podem ser usadas para autenticação do usuário. AuthorizedKeysFile pode conter tokens do formulário% T que são substituídos durante a configuração da conexão. Os seguintes tokens são definidos: %% é substituído por um literal '%',% h é substituído pelo diretório inicial do usuário que está sendo autenticado e% u é substituído pelo nome de usuário desse usuário. Após a expansão, AuthorizedKeysFile é considerado um caminho absoluto ou relativo ao diretório inicial do usuário. O padrão é ".ssh / authorized_keys".

Talvez seja assim

AuthorizedKeysFile /etc/ssh/%u/authorized_keys