
32-5
Cisco Security Appliance Command Line Configuration Guide
OL-6721-01
Chapter 32 Monitoring and Troubleshooting
Troubleshooting the Security Appliance
Enabling ICMP Debug Messages and System Messages
Debug messages and system messages can help you troubleshoot why your pings are not successful. The
security appliance only shows ICMP debug messages for pings to the security appliance interfaces, and
not for pings through the security appliance to other hosts. To enable debugging and system messages,
perform the following steps:
Step 1 To show ICMP packet information for pings to the security appliance interfaces, enter the following
command:
hostname(config)# debug icmp trace
Step 2 To set system messages to be sent to Telnet or SSH sessions, enter the following command:
hostname(config)# logging monitor debug
You can alternately use logging buffer debug to send messages to a buffer, and then view them later
using the show logging command.
Step 3 To send the system messages to your Telnet or SSH session, enter the following command:
hostname(config)# terminal monitor
Step 4 To enable system messages, enter the following command:
hostname(config)# logging on
The following example shows a successful ping from an external host (209.165.201.2) to the security
appliance outside interface (209.165.201.1):
hostname(config)# debug icmp trace
Inbound ICMP echo reply (len 32 id 1 seq 256) 209.165.201.1 > 209.165.201.2
Outbound ICMP echo request (len 32 id 1 seq 512) 209.165.201.2 > 209.165.201.1
Inbound ICMP echo reply (len 32 id 1 seq 512) 209.165.201.1 > 209.165.201.2
Outbound ICMP echo request (len 32 id 1 seq 768) 209.165.201.2 > 209.165.201.1
Inbound ICMP echo reply (len 32 id 1 seq 768) 209.165.201.1 > 209.165.201.2
Outbound ICMP echo request (len 32 id 1 seq 1024) 209.165.201.2 > 209.165.201.1
Inbound ICMP echo reply (len 32 id 1 seq 1024) 209.165.201.1 > 209.165.201.2
The preceding example shows the ICMP packet length (32 bytes), the ICMP packet identifier (1), and
the ICMP sequence number (the ICMP sequence number starts at 0 and is incremented each time a
request is sent).
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