Child pipe communication closed - stdout.

Modified on Tue, 31 Oct, 2023 at 11:32 AM

Symptoms


Scenario #1:

Backup of any Unix server via Linux/MAC DS-Client using Unix-SSH backup sets.


Scenario #2:

Backup of Solaris servers via Linux /MAC DS-Client using Unix-SSH backup sets. When the Unix-SSH backup set is created, provide username and password and "su" to root and root password.

 

Cause


Scenario #1:

SSH Backup Sets may experience backup failures if the perl/python binary cannot be located using the path environment variable. In previous versions of the software, the DS-Client searched by default for the Perl path in several standard locations. The search for Perl/Python binaries is not performed starting with v.6.2 SP1.


Scenario #2:

a) The sudo is not found on source computer.

b) the csh or tcsh is used on the source computer, shells that are not supported

 

Workaround


Scenario #1:

Starting with v.6.2 Service Pack 1, this search is not performed (Perl/Python are executed directly) and if the path environment variable is not configured, the SSH backup activities will fail. If you experience such failures, the user has 2 options:

- add Perl/Python in the default search path on the target computer (check that "ssh –l perl" works from the DS-Client machine) or

- configure the Perl’s/Python's full path on the target machine in the backup set's "Advanced Connection" dialog -> "Interpreter/Program path" option.


Scenario #2:

a) Identify the path to sudo:

- Run the command:


which sudo


- Create a soft link to the path returned by the command above( e.g. to /usr/local/bin):

sudo ln -s /usr/local/bin/sudo /usr/bin


b) use sh root@ip_address


your ssh running on a custom port? Can you check in your sudoers file (on the source) if there is the line requiretty? What version of Linux is the source machine?


Configuration:

ssh_config and sshd_config configuration:

In ssh_config (on DS-Client)


add:


ServerAliveInterval 100


ServerAliveCountMax 6


 


In /etc/ssh/sshd_config


add (or change the values if they exist):


ClientAliveInterval 30


TCPKeepAlive yes


ClientAliveCountMax 99999


Restart the sshd service.


 


Many routers timeout the connection after some period of inactivity. For users of ssh, this can a big nuisance. In presence of such routers a ssh connection with no activity (for a few minutes) will disconnect automatically. The workaround is that the server and client keep talking to each other. This can be achived using one of the two ways:


Server Side Add the following two lines to /etc/ssh/sshd_config. This will make the server poll for client every 30 seconds. If the client fails to respond for 6 times (i.e., 3 mins), the server will close the connection. Note that this applies to version 2 of OpenSSH only.


ClientAliveInterval 30


ClientAliveCountMax 6


 


Client Side Add the following two lines to /etc/ssh/ssh_config (or $HOME/.ssh/config if you don't have root access). This will make the client poll for server every 30 seconds. If the servers fails to respond for 6 times (i.e., 3 mins), the client will close the connection. Note that this also applies to version 2 of OpenSSH only. ServerAliveInterval 30


ServerAliveCountMax 6


What does seem to work is to start a continuous ICMP echo request (ping) against the DS-System server.


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