Contents ixGFirewall design rules......................................... 13-32Filter basics ..................................................... 13-35Example filters ................................................. 13-36Chapter 14 — Utilities and Diagnostics ...................................14-1Ping ............................................................................ 14-2Trace Route................................................................. 14-5Telnet client................................................................. 14-6Disconnect Telnet console session ............................... 14-7Factory defaults........................................................... 14-7Transferring configuration and firmware files with TFTP.... 14-8Updating firmware .............................................. 14-8Downloading configuration files ........................... 14-9Uploading configuration files ............................. 14-10Transferring configuration and firmware files withXMODEM................................................................... 14-10Updating firmware ............................................ 14-11Downloading configuration files ......................... 14-12Uploading configuration files ............................. 14-12Restarting the system................................................ 14-13Part III: AppendixesAppendix A — Troubleshooting..................................................A-1Configuration problems .................................................. A-1Console connection problems ............................... A-2Network problems ................................................ A-2How to reset the router to factory defaults ...................... A-3Power outages............................................................... A-3Technical support .......................................................... A-4How to reach us................................................... A-4Appendix B — Understanding IP Addressing ..............................B-1What is IP?.................................................................... B-1About IP addressing ....................................................... B-1