Most Cisco devices use the syslog protocol to manage system logs and alerts. But unlike their PC and server counterparts, Cisco devices lack large internal storage space for storing these logs. To overcome this limitation, Cisco devices offer the following two options:
* Internal buffer— The device’s operating system allocates a small part of memory buffers to log the most recent messages. The buffer size is limited to few kilobytes. This option is enabled by default. However, when the device reboots, these syslog messages are lost.
* Syslog— Use a UNIX-style SYSLOG protocol to send messages to an external device for storing. The storage size does not depend on the router’s resources and is limited only by the available disk space on the external syslog server. This option is not enabled by default.
Proactive monitoring of firewall logs is an integral part of a Netadmin’s duties. The firewall syslogs are useful for forensics, network troubleshooting, security evaluation, worm and virus attack mitigation, and so on. The configuration steps for enabling syslog messaging on a PIX are conceptually similar to those for IOS- or CatOS-based devices. To configure a Cisco PIX Firewall with PIX OS 4.4 and above,
Table 4-13. PIX Configuration for Syslog
Step Command
1 Pixfirewall# config terminal
2 Pixfirewall(config)#logging timestamp
3 Pixfirewall(config)#logging hostinterface connected to syslog server] ip_address [protocol / port] [
4 Pixfirewall(config)#logging facilityfacility
5 pixfirewall(config)#logging trap level
6 pixfirewall(config)#logging on
7 pixfirewall(config)#no logging message
8 pixfirewall(config)#exit
Example 4-14 prepares the Cisco PIX Firewall to send syslog messages at facility local5 and severity debug and below to the syslog server. The Netadmin does not want the PIX to log message 111005. The syslog server has an IP address of 192.168.0.30
Example 4-14. Configuring a Cisco PIX Firewall for Syslog
Firewall-Dallas#
Firewall-Dallas# config terminal
Firewall-Dallas(config)# loggin time
Firewall-Dallas(config)# logging host 192.168.0.30
Firewall-Dallas(config)# logging facility 21
Firewall-Dallas(config)# logging trap 7
Firewall-Dallas(config)# logging on
Firewall-Dallas(config)# no logging message 111005
rewall-Dallas(config)# exit
Firewall-Dallas# show logging
Syslog logging: enabled
Facility: 21
Timestamp logging: enabled
Standby logging: disabled
Console logging: disabled
Monitor logging: disabled
Buffer logging: disabled
Trap logging: level debugging, 6 messages logged
Logging to inside 192.168.0.30
History logging: disabled
Device ID: disabled
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