check_http

This plugin will attempt to open an HTTP connection with the host.
Successful connects return STATE_OK, refusals and timeouts return STATE_CRITICAL other errors return STATE_UNKNOWN. Successful connects, but incorrect reponse messages from the host result in STATE_WARNING return values. If you are checking a virtual server that uses 'host headers' you must supply the FQDN (fully qualified domain name) as the [host_name] argument.
This plugin can also check whether an SSL enabled web server is able to serve content (optionally within a specified time) or whether the X509 certificate is still valid for the specified number of days.
Examples: CHECK CONTENT: check_http -w 5 -c 10 –ssl -H www.verisign.com

Usage: check_http -H <vhost> | -I <IP-address> [-u <uri>] [-p <port>]
       [-w <warn time>] [-c <critical time>] [-t <timeout>] [-L]
       [-a auth] [-f <ok | warn | critcal | follow>] [-e <expect>]
       [-s string] [-l] [-r <regex> | -R <case-insensitive regex>] [-P string]
       [-m <min_pg_size>:<max_pg_size>] [-4|-6] [-N] [-M <age>] [-A string]
       [-k string] [-S] [-C <age>] [-T <content-type>]

Options:
 -h, --help
    Print detailed help screen
 -V, --version
    Print version information
 -H, --hostname=ADDRESS
    Host name argument for servers using host headers (virtual host)
    Append a port to include it in the header (eg: example.com:5000)
 -I, --IP-address=ADDRESS
    IP address or name (use numeric address if possible to bypass DNS lookup).
 -p, --port=INTEGER
 Port number (default: 80)
 -4, --use-ipv4
    Use IPv4 connection
 -6, --use-ipv6
    Use IPv6 connection
 -S, --ssl
   Connect via SSL. Port defaults to 443
 -C, --certificate=INTEGER
   Minimum number of days a certificate has to be valid. Port defaults to 443
   (when this option is used the url is not checked.)

 -e, --expect=STRING
    String to expect in first (status) line of server response (default:
HTTP/1.)
    If specified skips all other status line logic (ex: 3xx, 4xx, 5xx processing)
 -s, --string=STRING
    String to expect in the content
 -u, --url=PATH
    URL to GET or POST (default: /)
 -P, --post=STRING
    URL encoded http POST data
 -N, --no-body
    Don't wait for document body: stop reading after headers.
    (Note that this still does an HTTP GET or POST, not a HEAD.)
 -M, --max-age=SECONDS
    Warn if document is more than SECONDS old. the number can also be of
    the form "10m" for minutes, "10h" for hours, or "10d" for days.
 -T, --content-type=STRING
    specify Content-Type header media type when POSTing

 -l, --linespan
    Allow regex to span newlines (must precede -r or -R)
 -r, --regex, --ereg=STRING
    Search page for regex STRING
 -R, --eregi=STRING
    Search page for case-insensitive regex STRING
 --invert-regex
    Return CRITICAL if found, OK if not

 -a, --authorization=AUTH_PAIR
    Username:password on sites with basic authentication
 -A, --useragent=STRING
    String to be sent in http header as "User Agent"
 -k, --header=STRING
     Any other tags to be sent in http header. Use multiple times for additional headers
 -L, --link
    Wrap output in HTML link (obsoleted by urlize)
 -f, --onredirect=<ok|warning|critical|follow>
    How to handle redirected pages
 -m, --pagesize=INTEGER<:INTEGER>
    Minimum page size required (bytes) : Maximum page size required (bytes)
 -w, --warning=DOUBLE
    Response time to result in warning status (seconds)
 -c, --critical=DOUBLE
    Response time to result in critical status (seconds)
 -t, --timeout=INTEGER
    Seconds before connection times out (default: 10)
 -v, --verbose
    Show details for command-line debugging (Nagios may truncate output)

Q: Kann ich mit check_http auch passwortgeschützte Webseiten prüfen?

A: Ja. Über die Option -a lassen sich Username und Passwort übergeben.
Security Related:
Username/Passwort in der Nagios Config (service definitionen / command definitionen / etc.) anzugeben lässt die Möglichkeit zu, dass man auch über das Nagios Webinterface sich diese Sachen unter dem Punkt View Config ansehen kann.
Man kann allerdings geheime Daten in die sog. ressource.cfg als $USERx$ Makro stecken und im Pluginaufruf darüber wieder zugreifen.
Konfigurationen aus der ressource.cfg werden nicht über das Nagios Webinterface dargestellt.