Wednesday, October 14, 2009

Zenoss monitor Windows Server 2008 via WMI

Zenoss supports Windows SNMP, it can get partition and interfaces infomation, but it couldn't get CPU/MEMORY info. WMI script can get almost any info in Windows. Zenoss supports Windows WMI by zenpack
The agent account in remote Windows Server doens't need to be admin user as long as following previleges granted.

Enable DCOM
The easy way is to add the user to group "Distributed COM users"

Alternatively, grant specific rights to the user
Start DCOM GUI by DCOMCNFG command-> Component Services -> Computers->Right-click My Computer, and then select Properties->COM Security tab
Give access permission and launch and activation permission.

Enabling Account Privileges in WMI
Computer Management -> Services and Applications-> WMI Control->right click select Properties->Security
Select CIMV2 under root

Select security button add new user with
Enable Account
Remote Enable

Allowing WMI through the Windows Firewall
Allow pre-defined rule: Windows Management Instrumentation (WMI)

Deny ssh interactive login but allow sftp

SSH interactive login need tty to be allocated but sftp/scp doesn't need tty. So you can disable SSH interactive login by no-pty option in OPENSSH. But no-pty option is valid only in public key authentication, so you have to disable password for the user with “passwd –l username” command.

I have attempted to use tty option to achieve this, I found it is impossible because pam_tty name ssh will be allocated in either ssh login or sftp.

All you need to is to put no-pty parameter in ~/.ssh/authorized_keys, it must be in the same line with the public key, multiple options are separated by comma e.g

no-pty,no-X11-forwarding ssh-dss AAAAB3Nz ... key-comment

Another useful feature of public key authentication is forced command, which means the command is invoked whenever the key is authenticated, it is great security feature for remote execution e.g backup job. you can also limit client source with "from= " option.

#Force to run command date only
$ cat /home/test/.ssh/authorized_keys
command="date" ssh-dss AAAAB3NzaC1kc3 ..

#date command was executed even given command is ls
$ ssh test@localhost ls
Wed Oct 14 10:29:39 EST 2009

#forced command can literally disable SSH interactive login.
$ ssh test@localhost
Wed Oct 14 10:29:44 EST 2009
Connection to localhost closed.