If you need to filter out duplicate IP addresses in a log file, use the uniq command-line tool. This command is the same as grep, but with the addition of regular expression syntax. It will find IP addresses in a log file and return counts for each one. This example shows how to filter two IP addresses that appeared 42 and 16 times, respectively. This method can be used for nearly any situation where you need to search for IP addresses.
Configuring a logging host
Logging is an important process that helps to manage risk and technology. This process can be enforced by configuring a logging host IP address. This IP address determines which devices send system logging messages to the logging host and which devices receive those messages. The severity of the logged messages can be set to informational or high.
The syslog host IP address can be either a local or remote address. The syslog server can collect and store logs for long-term analysis using your preferred analytic tool. To configure a remote syslog server, you must have Read-Write permission for the Log & Report settings. You must also configure the listening port, which is typically UDP port 514. The debug information contained in the logged messages can be used to diagnose and fix unexpected behavior.
Specifying a source IP address
You can configure your router to use a source IP address for logging. This feature is very useful if you have a dual-stack network and you need to troubleshoot some problems. It 192.168.o.1 allows you to view the logging information on both sides of the connection.
You can specify a single port, or a range of ports. If you specify a single port, make sure to enter the port number in the first field. For example, if you specify a port number of 10, make sure to enter the low port first. You can also specify a destination IP address or a subnet.
Using a VLAN interface as a source IP address
A VLAN interface is a virtual interface that is associated with a Layer 3 VLAN. It allows you to route traffic between VLANs on a device without using an external router. Layer 3 switches support VLANs by using a feature called Integrated Switch Routing. When you create a VLAN interface, you must specify a name for it. The name should be the same as the VLAN.
You can use a VLAN interface for logging by using the ip source-interface command. The source IP address can be a VLAN interface or a loopback interface. When you use a VLAN interface, make sure you configure the IP address that you want to use as the source address. Then, use the show command to display its status.
Using a configured IP address
To use a configured IP address for logging, you must have a management IP address configured on your blade. This IP address must be able to send logs out. If you do not have a management IP address, the secondary blade will use the default IP address of the cluster. To configure a management IP address, go to the Configuration utility on your server. In the Configuration utility, navigate to System> Logs> Configuration> Log Destinations. On the Configuration utility’s log destination screen, enter the name of the destination log server, IP address, and port. You can also manually specify the IP address in the IP address field.
Using a configured IP interface as a source IP address
In Cisco IOS, a source IP address can be configured on either an inbound or outgoing interface. This will allow you to use a different IP address for different software applications or set a single source IP address for all IP traffic. This article shows you how to configure a source IP address for logging.
When using a source IP address for logging, you should use a different address for the interface than what is configured in the management VRF. This will ensure that logging messages are attributed to the correct device. Also, the source IP address should not change as the network topology changes. However, you should note that the source IP address of syslog is not encrypted and may be vulnerable to a MiTM attack. If you are using a network that is susceptible to such attacks, you should use a separate VRF for the interface you are configuring.