Syslog message format

Syslog messages that appear on a Cisco device consists of several parts. Consider the following message:*Jan 18 03:02:42: %LINEPROTO-5-UPDOWN: Line protocol on Interface GigabitEthernet0/0, changed state to downThe message consists of the following parts:Jan 18 03:02:42 Рthe timestamp%LINEPROTO Рthe source that generated the message. It can be a hardware device (e,g. a router), a protocol, or a module of the system software.5 Рthe severity level, from 0 to 7, with lower numbers Read more [...]

Syslog explained

Syslog is a standard for message logging. Syslog messages are generated on Cisco devices whenever an event takes place – for example, when an interface goes down or a port security violation occurs.You’ve probably already encountered syslog messages when you were connected to a Cisco device through the console – Cisco devices show syslog messages by default to the console users:R1# %LINEPROTO-5-UPDOWN: Line protocol on Interface GigabitEthernet0/0, changed state to downThis is because Read more [...]

Cisco console rollover cable

A rollover cable is usually shipped with each Cisco device. This cable connects a serial port on your computer to the console port of the device and it is used for the device’s initial configuration. It is called rollover because the wires on one end are rolled at the other end – the wire at pin 1 connects to the pin 8 on the other side, the wire at pin 2 to the pin 7, etc.The cable is of light blue color with a DB-9 connector at one end and a RJ-45 connector at the other:You connect Read more [...]

Encrypt local usernames and passwords

We’ve learned it is possible to configure local usernames and passwords on a Cisco device and then use them to login to the device. To do this, we’ve used the username USER password PASSWORD command, like in the example below:R1(config)#username tuna password peyoHowever, there is one problem with this command – the password is stored in clear text in the configuration:R1#show running-config Building configuration... Current configuration : 635 bytes ! version 15.1 .... ! username Read more [...]

Auxiliary Port on a Cisco router

Most Cisco routers include an additional auxiliary (Aux) port as a backup async port. This port is commonly used as a dial-up port for remote router management. It is connected to a modem and enables an administrator to make a phone call to connect to the router’s CLI.The following figure shows how to connect a modem to an aux port on a router (image source: Cisco):The network administrator uses a terminal emulation program to connect to the router over the aux port. The configuration of the Read more [...]

no ip domain-lookup command

By default, any single word entered on an IOS device that is not recognized as a valid command is treated as a hostname to which you want to telnet. The device will try to translate that word to an IP address in a process that can last about a minute.Consider the following example:R1#writte Translating \"writte\"...domain server (255.255.255.255) % Unknown command or computer name, or unable to find computer addressIn the output above you can see that I’ve mistyped the command write. The router Read more [...]