Prerequisites for Adding the Linux Host to CHAI™ for Discovery¶

Recommended Resource Requirements¶

Resource	CPU	RAM	/home/	/opt
Requirement	4 cores	8 GB	> 500 MB	> 2 GB

Discovery uses /opt partition for its operation. Please allow the executable permissions to the folder. Verify it as follows on the Host:

[ssh-user@host ~]$ ls -ltr /opt
drwxr-xr-x  9 root  testdir  288 Sep 27  2016 X11   

"x" is required which ensures the execute permission.

Privilege Access¶

User account used for connection between CHAI™ and host must have privilege access.

Below line can be added to the END of the file - /etc/sudoers for allowing connecting user to communicate without password certain commands. Please update the path for system commands like mkdir, echo etc:

<ssh-user-for-CHAI-host> ALL=(ALL) NOPASSWD:/opt/.ch-tools/*/*/*, /opt/.ch-tools/*/*, /bin/mkdir, /bin/echo, /bin/chmod 755 /opt/.ch-tools/*, /bin/chmod 755 /home/<ssh-user-for-CHAI-host>/chcmd, /bin/chmod -R 755 /opt/.ch-tools, /bin/chmod -R 755 /home/<ssh-user-for-CHAI-host>/.ch-tools, /bin/chown <ssh-user-for-CHAI-host>\: /opt/.ch-tools/*, /bin/chown -R <ssh-user-for-CHAI-host>\: /home/<ssh-user-for-CHAI™-host>/chcmd, /bin/chown -R <ssh-user-for-CHAI-host>\: /opt/.ch-tools, /bin/chown -R <ssh-user-for-CHAI-host>\: /home/<ssh-user-for-CHAI-host>/.ch-tools

RequireTTY¶

Disable requiretty for connecting user from remote machine to Host. If set, sudo will only run when user is logged in to a real terminal and not via other means such as cron, cgi-bin or ssh scripts. Since CHAI™ connects to the Host remotely without a real terminal, this flag must be disabled. This flag is off by default. Below line can be added to /etc/sudoers file:

Defaults:<ssh-user-for-CHAI-host>    !requiretty

SSHD Server¶

The ssh server (sshd) must be running on the host. Verify it as follows on the Host:

[ssh-user@host ~]$ ps ax | grep <sshd or openssh or equivalent>

Connection between Host and CHAI™¶

CHAI™ authenticates with the Linux Host using the following 2 methods over ssh:

Username and ssh key
Username and password

Host communicates back to CHAI™ over port 443 (https). Please ensure that port 443 is enabled on the Host for external communication and unblocked on the firewall in between Host and CHAI™.