Chapter 19: Decoding Application-Layer Protocols 19-1 Copyright © 1998, Cisco Systems, Inc.

19-2MCSIDecoding Application-Layer Protocols Copyright © 1998, Cisco Systems, Inc. Identify what protocol decoding is Identify why protocol decoding should be used Identify when protocol decoding should be used Start the Protocol Decode tool Objectives

19-3MCSIDecoding Application-Layer Protocols Copyright © 1998, Cisco Systems, Inc. Objectives (cont.) Capture packets Display captured packet contents Display packets in hex Apply postcapture filters

19-4MCSIDecoding Application-Layer Protocols Copyright © 1998, Cisco Systems, Inc. Capturing packets Filtering packets Displaying packet contents in plain English What Is Protocol Decoding?

19-5MCSIDecoding Application-Layer Protocols Copyright © 1998, Cisco Systems, Inc. Troubleshooting Communication failures Complex routing problems Catching security violators Why Decode Protocols?

19-6MCSIDecoding Application-Layer Protocols Copyright © 1998, Cisco Systems, Inc. Troubleshooting Security monitoring When Should Protocol Decoding Be Used?

19-7MCSIDecoding Application-Layer Protocols Copyright © 1998, Cisco Systems, Inc. Capturing Packets

19-8MCSIDecoding Application-Layer Protocols Copyright © 1998, Cisco Systems, Inc. Capturing Packets (cont.)

19-9MCSIDecoding Application-Layer Protocols Copyright © 1998, Cisco Systems, Inc. Completing the Packet Capture

19-10MCSIDecoding Application-Layer Protocols Copyright © 1998, Cisco Systems, Inc. Displaying Packet Contents

19-11MCSIDecoding Application-Layer Protocols Copyright © 1998, Cisco Systems, Inc. Decoding Protocol Layers

19-12MCSIDecoding Application-Layer Protocols Copyright © 1998, Cisco Systems, Inc. Displaying Packets in Hex

19-13MCSIDecoding Application-Layer Protocols Copyright © 1998, Cisco Systems, Inc. Applying Postcapture Filters

19-14MCSIDecoding Application-Layer Protocols Copyright © 1998, Cisco Systems, Inc. Identify what protocol decoding is Identify why protocol decoding should be used Identify when protocol decoding should be used Start the Protocol Decode tool Summary

19-15MCSIDecoding Application-Layer Protocols Copyright © 1998, Cisco Systems, Inc. Capture packets Display captured packet contents Display packets in hex Apply postcapture filters Summary (cont.)

19-16MCSIDecoding Application-Layer Protocols Copyright © 1998, Cisco Systems, Inc. Blank for IG Pagination