check-host-alive check

[Marc Powell]

On Feb 5, 2009, at 2:42 AM, mariog at absi.be wrote:

>
> Hello all,
> and thank you i found the check-host-alive in the files  
> checkcommands.cfg in the nagios conf directory.
> now what is startles me is that there are 100% packet loss however  
> the host is up in nagios,

Sounds like you have a firewall or iptables that's not permitting  
ICMP. It seems fixable but your policies may say otherwise.

> it just the service check-host alive that is critical;

You have a service{} definition that uses check-host-alive? If the  
host is not pingable and you're trying to have nagios ping it, it's  
logical that it would show CRITICAL.

> what are the arguments of nagios to say that a host is up or down..  
> i thought it was a ping but if the ping from the nagios server to  
> the host doesn't work how can it say it's up?

In the host{} definition, the results of the check_command will  
determine if it's up or down. You can run it from the command line as  
the nagios user to see what it'll do. Be sure to substitute the $MACROS 
$ with their correct values. If that check_command doesn't return  
accurate status, use something else that does or fix ping.

> are all host up by default? how can you make them down when a ping  
> cannot be performed.

Specify a check_command that would accurately reflect the status of  
the host. What that is depends on the device you are monitoring and  
what you believe accurately reflects it's status. For example, if the  
host only provides HTTP service and if HTTP doesn't work the host is  
effectively down, a host check_command of check_http might be  
appropriate.

> in the host status information there is NA still the host is shown  
> as up..

Sounds like you're using Nagios-2. In that version, hosts are not  
checked, and assumed to be up until a service on the host returns a  
non-OK result. The host is then checked with it's specified  
check_command to determine it's status.

--
Marc

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