ssh connections dropping

[Tapas Mishra]

On Thu, Feb 10, 2011 at 4:43 PM, Tapas Mishra <mightydreams at gmail.com> wrote:
> Here is a situation I have just restored Ubuntu server which had kvm
> running on it.
> Every thing went fine and I copied the /etc/libvirt/qemu/vm.xml from
> backup to new installation where it was previously running.
> But this time I see that SSH connections to the guest drop after some time.
> Even a reboot does not help.
> I have to shut down the guest and wait for a second or two and the power it on.
>
> The error that I get is
>
> ssh -vvv root at 192.168.1.5
> OpenSSH_5.1p1 Debian-5ubuntu1, OpenSSL 0.9.8g 19 Oct 2007
> debug1: Reading configuration data /etc/ssh/ssh_config
> debug1: Applying options for *
> debug2: ssh_connect: needpriv 0
> debug1: Connecting to 192.168.1.5 [192.168.1.5] port 22.
> debug1: connect to address 192.168.1.5 port 22: No route to host--
>
>
>
> The sshd_config file on guest is here
>
> # 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
> #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 /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
>
>
>
> Reboot of the guest OS does not help I have to shutdown
>  it and after waiting for some time I start it again.
>


Carsten Aulbert <carsten.aulbert at aei.mpg.de>

On Thu, Feb 10, 2011 at 4:51 PM, Carsten Aulbert
<carsten.aulbert at aei.mpg.de> wrote:
> Hi
>
> On Thursday 10 February 2011 12:13:16 Tapas Mishra wrote:
>> debug1: Connecting to 192.168.1.5 [192.168.1.5] port 22.
>> debug1: connect to address 192.168.1.5 port 22: No route to host--
>
> This indicates your client don't know how to talk to 192.168.1.5 (or the
> "network" in-between doesn't know).
Yes I understand this part that is why I am concerned.
> Is the machine really fully running? Is the network working?  Is routing
> correct?
This part is correct I can confirm here.






On Thu, Feb 10, 2011 at 5:00 PM, Hugo Serrano <hugo.serrano at javali.pt> wrote:
> Hi.
>
> Check the IP address in the guest machine.
>
> Do you got static IP?
Yes
> Is there any dhclient process running?
No

Any other suggestions here?