[Nagiosplug-help] check_icmp oddness

[Andreas Ericsson]

Israel Brewster wrote:
> On Apr 4, 2008, at 1:42 AM, Andreas Ericsson wrote:
>> Israel Brewster wrote:
>>> I am having some difficulty using the check_icmp plugin to monitor a  
>>> number of my hosts, specifically Linksys RV082 routers running the  
>>> latest firmware. What's happening is if I have a command line such as:
>>> ./check_icmp -n 2 -m 1 -w 3000,80% -c 5000,100% xx.xxx.xxx.111  
>>> xx.xxx.xxx.33
>>
>> Add '-i 0.5s' to the command line and it might just magically start
>> working. That will increase the packet interval, which can sometimes
>> be too short when sending to a single host with multiple IP's.
>> Especially if there's a firewall in between.
> 
> Well, that partially worked. If I increase that value to a ridiculously 
> high amount (>10s) the packet loss drops to only about 33% (with 5 
> pings) rather than the 60% I get with the default settings. The pattern, 
> however, is the same- only the first x packets received, where x is a 
> constant in relation to the number of packets sent. One thing I find a 
> bit confusing- the help text lists the -i switch as the "MAX packet 
> interval". What determines the min? I would thing the minimum packet 
> interval would be more of an issue than the maximum, although perhaps 
> not considering that setting the maximum did make a difference. Thanks 
> again!
> 

The minimum packet interval is determined as "if we've already seen
replies to all packets we sent to this host, it's probably ready to
get another one, so send it out instantly."

-I (capital i) is used to set a target_interval, which is used as
the minimum value to wait between two packets going to the same
target. I'm not sure if that switch exists in the check_icmp.c the
nagiosplug project ships, but it does in the one I've got.

-- 
Andreas Ericsson                   andreas.ericsson at op5.se
OP5 AB                             www.op5.se
Tel: +46 8-230225                  Fax: +46 8-230231