I have set up a home network behind a router a while ago and use openssh to access the network consisting of my laptop, wife's netbook and my desktop all running l/x/ubuntu 12.04. This worked perfectly for some time.

I am now only able to access from and to the netbook and the other 2, but no access between the laptop and desktop. I have never used the id_* route so have no id_* files in the ~/.ssh directories.

I have tried various strategies advised on forums such as this one eg. deleting the known_hosts and changing the configuration files such as the PasswordAuthentication to no, yes and commented out. None of which works.

The only thing I can think of is that my recent tinkering with setting up a vpn network between the laptop and desktop may have changed something to disrupt the working of ssh between these 2 machines. btw I have not managed to get the vpn to work yet (see previous post on this forum).

The /etc/ssh/sshd_config file on my desktop is:

# Package generated configuration file

# See the sshd_config(5) manpage for details



# What ports, IPs and protocols we listen for

Port 22

# Use these options to restrict which interfaces/protocols sshd will bind to

#ListenAddress ::

#ListenAddress 0.0.0.0

Protocol 2

# HostKeys for protocol version 2

HostKey /etc/ssh/ssh_host_rsa_key

HostKey /etc/ssh/ssh_host_dsa_key

HostKey /etc/ssh/ssh_host_ecdsa_key

#Privilege Separation is turned on for security

UsePrivilegeSeparation yes



# Lifetime and size of ephemeral version 1 server key

KeyRegenerationInterval 3600

ServerKeyBits 768



# Logging

SyslogFacility AUTH

LogLevel INFO



# Authentication:

LoginGraceTime 120

PermitRootLogin yes

StrictModes yes



RSAAuthentication yes

PubkeyAuthentication yes

#AuthorizedKeysFile %h/.ssh/authorized_keys



# Don't read the user's ~/.rhosts and ~/.shosts files

IgnoreRhosts yes

# For this to work you will also need host keys in /etc/ssh_known_hosts

RhostsRSAAuthentication no

# similar for protocol version 2

HostbasedAuthentication no

# Uncomment if you don't trust ~/.ssh/known_hosts for RhostsRSAAuthentication

#IgnoreUserKnownHosts yes



# To enable empty passwords, change to yes (NOT RECOMMENDED)

PermitEmptyPasswords no



# Change to yes to enable challenge-response passwords (beware issues with

# some PAM modules and threads)

ChallengeResponseAuthentication no



# Change to no to disable tunnelled clear text passwords

#PasswordAuthentication yes



# Kerberos options

#KerberosAuthentication no

#KerberosGetAFSToken no

#KerberosOrLocalPasswd yes

#KerberosTicketCleanup yes



# GSSAPI options

#GSSAPIAuthentication no

#GSSAPICleanupCredentials yes



X11Forwarding yes

X11DisplayOffset 10

PrintMotd no

PrintLastLog yes

TCPKeepAlive yes

#UseLogin no



#MaxStartups 10:30:60

#Banner /etc/issue.net



# Allow client to pass locale environment variables

AcceptEnv LANG LC_*



Subsystem sftp internal-sftp #/usr/lib/openssh/sftp-server



# Set this to 'yes' to enable PAM authentication, account processing,

# and session processing. If this is enabled, PAM authentication will

# be allowed through the ChallengeResponseAuthentication and

# PasswordAuthentication.  Depending on your PAM configuration,

# PAM authentication via ChallengeResponseAuthentication may bypass

# the setting of "PermitRootLogin without-password".

# If you just want the PAM account and session checks to run without

# PAM authentication, then enable this but set PasswordAuthentication

# and ChallengeResponseAuthentication to 'no'.

UsePAM yes



Match User sftpuser #group sftponly

ChrootDirectory /media/Backups/ftp

X11Forwarding yes

AllowTcpForwarding yes 

ForceCommand internal-sftp

The ssh -v laptop command outputs:

OpenSSH_5.9p1 Debian-5ubuntu1.1, OpenSSL 1.0.1 14 Mar 2012

debug1: Reading configuration data /home/malapradej/.ssh/config

debug1: /home/malapradej/.ssh/config line 1: Applying options for laptop

debug1: Reading configuration data /etc/ssh/ssh_config

debug1: /etc/ssh/ssh_config line 19: Applying options for *

debug1: Connecting to 192.168.0.2 [192.168.0.2] port 22.

debug1: Connection established.

debug1: identity file /home/malapradej/.ssh/id_rsa type -1

debug1: identity file /home/malapradej/.ssh/id_rsa-cert type -1

debug1: identity file /home/malapradej/.ssh/id_dsa type -1

debug1: identity file /home/malapradej/.ssh/id_dsa-cert type -1

debug1: identity file /home/malapradej/.ssh/id_ecdsa type -1

debug1: identity file /home/malapradej/.ssh/id_ecdsa-cert type -1

debug1: Remote protocol version 2.0, remote software version OpenSSH_5.9p1 Debian-5ubuntu1.1

debug1: match: OpenSSH_5.9p1 Debian-5ubuntu1.1 pat OpenSSH*

debug1: Enabling compatibility mode for protocol 2.0

debug1: Local version string SSH-2.0-OpenSSH_5.9p1 Debian-5ubuntu1.1

debug1: SSH2_MSG_KEXINIT sent

debug1: SSH2_MSG_KEXINIT received

debug1: kex: server->client aes128-ctr hmac-md5 [email protected]

debug1: kex: client->server aes128-ctr hmac-md5 [email protected]

debug1: sending SSH2_MSG_KEX_ECDH_INIT

debug1: expecting SSH2_MSG_KEX_ECDH_REPLY

debug1: Server host key: ECDSA 1e:f2:57:81:28:8a:12:d3:7e:2d:04:c2:82:4f:43:72

debug1: Host '192.168.0.2' is known and matches the ECDSA host key.

debug1: Found key in /home/malapradej/.ssh/known_hosts:1

debug1: ssh_ecdsa_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

debug1: Next authentication method: publickey

debug1: Trying private key: /home/malapradej/.ssh/id_rsa

debug1: Trying private key: /home/malapradej/.ssh/id_dsa

debug1: Trying private key: /home/malapradej/.ssh/id_ecdsa

debug1: No more authentication methods to try.

Permission denied (publickey).