Tools for easily and automatically initializing/renewing Kerberos tickets with launchd and from command-line scripts on Snow Leopard.

.profile.functions

# Initialize or renew Kerberos tickets. Assumes password for the requested principal is stored in the 
# keychain, which is now automatically used by Snow Leopard kinit.
# This is useful to define globally in your shell profile, for easy use within other scripts and 
# from the command-line.
function ker {
	kinit -R 2> /dev/null
	if [[ $? = '0' ]]; then
		echo "renewed..."
		klist
	else
		kinit $1
		klist
	fi
}

# Test whether the machine is online.
function network_is_connected {
    
    oldwired=$wired
    oldwireless=$wireless
    unset wired
    unset wireless

    wiredStatus=`ifconfig en0 | grep status | grep -vc inactive`
    wirelessStatus=`ifconfig en1 | grep status | grep -vc inactive`
    
    if [[ $wiredStatus != "0" ]]; then
        wired=true
    fi

    if [[ $wirelessStatus != "0" ]]; then
        wireless=true
    fi

    if [[ $wired || $wireless ]]; then
        echo "true"
    else
        echo "false"
    fi
    
    wired=$oldwired
    wireless=$oldwireless
}

README.txt

To initialize Keychain entries for your Kerberos principal(s) in 10.6, the simplest method is to run kinit with no attached tty, e.g.:

    echo | kinit [principal]

or

    kinit [principal] < /dev/null

edu.mit.jrk.RenewKerberosTickets.plist

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
<dict>
	<key>Disabled</key>
	<false/>
	<key>Label</key>
	<string>edu.mit.jrk.RenewKerberosTickets</string>
	<key>ProgramArguments</key>
	<array>
		<string>/path/to/bin/renewKerberos.sh</string>
	</array>
	<key>RunAtLoad</key>
	<true/>
	<key>StartInterval</key>
	<integer>3600</integer>
</dict>
</plist>

renewKerberos.sh

#!/bin/bash

source ~/.profile.functions

if [[ `network_is_connected` == "true" ]]; then
    ker $MyPrincipal
else
    echo "renewKerberos: not renewing because not online"
fi