5.1.1 Changing the Settings for the Console Port
Of the three connections previously described, the console port is unique in that it is always used for the initial steps needed in configuration because it is by default the only interface that can be used to access the CLI on a Juniper Networks router. All other interfaces lack a functional configuration at initial startup. The console port is an RS232 male 9-pin connection on the craft interface of every Juniper Networks M-Series router. Refer to Figures 5-1 through 5-6 to identify the location of the console port connection on the craft interfaces of the routers.
By default the console port is considered to be secure in that it is permissible to log into the router as the root user through this connection. Those familiar with UNIX will recall that the root user has special permissions. In the Juniper Networks world, the root user is capable of accessing the UNIX kernel, as well as the core of JUNOS. Under normal conditions, root access should be permitted through the console. However, should a network engineer find it necessary, the console port can be blocked from allowing root access. The following example shows how to disable the root login on the console port:
[edit system ports console] lab@Chicago# set insecure
The default speed for the console connection is 9,600 baud. The following example shows the command completions for setting the connection speeds. By using the question mark, the valid completions for any command string can be accessed from any point within the JUNOS CLI.
[edit system ports console] lab@Chicago# set speed ? Possible completions: 115200 Standard terminal at 115200 baud 19200 Standard terminal at 19200 baud 38400 Standard terminal at 38400 baud 4800 Standard terminal at 4800 baud 57600 Standard terminal at 57600 baud 9600 Standard terminal at 9600 baud
If the baud rate on the console port is changed, any user logged in through that port will immediately be disconnected once the change is committed. The configuration sample below shows how to set the link speed for the console port to 19.2Kbps. It also shows user lab being logged off once the change is committed:
[edit system ports console] lab@Chicago# set speed 19200 [edit system ports console] lab@Chicago# show speed 19200; [edit system ports console] lab@Chicago# commit