Nagios: CRITICAL - Socket timeout after 10 seconds

Question

I've been running nagios for about two years, but recently this problem started appearing with one of my services.

I'm getting

CRITICAL - Socket timeout after 10 seconds

for a check_http -H my.host.com -f follow -u /abc/def check, which used to work fine. No other services are reporting this problem. The remote site is up and healthy, and I can do a wget http://my.host.com/abc/def from the nagios server, and it downloads the response just fine. Also, doing a check_http -H my.host.com -f follow works just fine, i.e. it's only when I use the -u argument that things break. I also tried passing it a different user agent string, no difference. I tried increasing the timeout, no luck. I tried with -v, but all it get is:

GET /abc/def HTTP/1.0
User-Agent: check_http/v1861 (nagios-plugins 1.4.11)
Connection: close
Host: my.host.com


CRITICAL - Socket timeout after 10 seconds

... which does not tell me what's going wrong.

Any ideas how I could resolve this?

Thanks!

Answer 1

Try using the -N option of check_http.

I ran into similar problems, and in my case the web server didn't terminate the connection after sending the response (https was working, http wasn't). check_http tries to read from the open socket until the server closes the connection. If that doesn't happen then the timeout occurs.

The -N option tells check_http to receive only the header, but not the content of the page / document.