To check the FritzBox 7490 with the latest firmware you could use the following script:
The syntax is:
./check_fritz -h <IP ADDRESS> -f <function> Where function can be: ipaddress (check the current external ip address) connection (check if the connection is up) linkuptime (Return the current uptime of the WAN link) downstream (Return the current download rate) upstream (Return the current upload rate)