[Xymon] http test

[Henrik Størner]

On 14-07-2013 15:15, Martin Flemming wrote:
> Can somebody tell me  how the http-check work ?
>
> .. i see nothing like "curl, etc." in the source
>
> xymonnet/httptest.c

Xymon does all of the HTTP request generation and network stuff by itself.


> The reason ist, that after a normal http-check on a windows-server,
> the application craches .. .i can't believe that the xymon-http-test
> should be the reason, but i've to tell how does xymon test a webside ...

Unfortunately, there is no debugging option in xymonnet so it shows 
exactly what is being sent to the server. And it depends on the exact 
test you have in hosts.cfg.

Assuming this is a simple URL test (no POST data or other special 
stuff), then a test like

	10.0.0.1  mywebserver	# http://web.example.com/myapp/

would trigger this request:

	GET /myapp/ HTTP/1.1
	Connection: close
	Host: web.example.com
	User-Agent: Xymon xymonnet/4.3.11
	Accept: */*
	Pragma: no-cache

My guess would be that it crashes on the "User-Agent" string because it 
doesn't handle unknown useragents (browsers) correctly. I've seen that 
happen.


A network sniffer on the Xymon server can tell you exactly what is being 
sent and received - e.g. wireshark. You can also use tcpdump or snoop 
and still analyse the data with wireshark - that is much easier than 
reading the raw output from tcpdump.


Regards,
Henrik