cas-simulation

A way to simulate a web browser visiting a service authenticated by CAS and proceeding through the authentication.

Originally developed to facilitate authenticated service checks in Nagios.

check_cas_sp

cas_simulation object instances are created using the included check_cas_sp script, intended to be called from Nagios

The simulation will follow redirects from a starting URL (typically a service provider like https://myportal.example.edu) until it reaches a form that it believes is a CAS authentication page (at least the one presented by the JASIG/Apereo implementation). It will then submit the form using the credentials provided. It will follow redirects and submit forms (e.g. "Click here to continue" javascript alternatives) until it receives a 200 OK page without a form, or the form contains an id or action attribute matching argument provided to the --form.

The final landing page is searched for an expected pattern using --expression. If it matches, the script returns 0 which corresponds to a OK in Nagios API. Otherwise it returns 2 for CRITICAL

Optionally, the check_cas_sp will also fetch and check an expression against a URL that is only expected to be available after authentication. This would simulate clicking a link on a portal after logging in.

Gotchas

Notably, the --verbose option stupidly assumes it can write to /var/log/nagios

Examples

check_cas_sp --help

List all current command line options

check_cas_sp \
    --url https://fee-portal.csusb.edu/auth/shibboleth" \
    --expression "Fines .{1,30}for Joe Coyote" \
    -w 5.0 \
    --post-auth-check https://fee-portal.csusb.edu/fines/alma "Balance [Dd]ue" \
    --credentials "/etc/cas/joe-creds.json" \

Authenticate fee-portal.csusb.edu using the credentials in /etc/cas/joe-creds.json. The post authentication redirect contains "Fines and fees for Joe Coyote" and should match the regular expression given.

After that check, also check a url that requires an authenticated active session. In this case, a check for the Alma library fees that should contain the text "Balance Due". Return WARNING if the authentication takes more than 5 seconds. (It probably should be --post-auth-url and --post-auth-expression instead of being combined like it is.)

check_cas_sp \
    --url https://my.csusb.edu \
    --expression 'Signed in as Joe Coyote<div .{1,30}>Tap to sign out' \
    -w 10 \
    --form '/default/kurogo_module_search/search' \
    --credentials credentails.json

Authenticate to my.csusb.edu and expect a name next to a "Tap to sign out" after authentication. Do not proceed past the form with the name or id of '/default/kurogo_module_search/search' Typically, the simulation will submit any forms it encounters, assuming they are "Click here to continue" type forms)

Examples Nagios command objects

define command {
        command_name    check-cas-sp
        command_line    /opt/virtualenv/cas-simulation/bin/check_cas_sp --url '$ARG1$' --expression '$ARG2$' $ARG3$ --verbose --credentials /etc/nagios/secrets/credentials.json
}

define command {
        command_name    check-cas-sp-post-auth
        command_line    /opt/virtualenv/cas-simulation/bin/check_cas_sp --url '$ARG1$' --expresison '$ARG2$' $ARG3$ --post-auth-check '$ARG4$' '$ARG5$' --verbose --credentials /etc/nagios/secrets/credentials.json
}