= Node Serial Console =

Some devices, like the USRP N310 and USRP 2974, have a serial console redirect that allows "out of band" access to their onboard system in case of network misconfiguration. The serial console is relatively slow and is not meant for normal experiment use. However, in cases where a device is no longer accessible via SSH, its serial console may be used to perform the repairs necessary to restore normal SSH access.

The serial console of a node is accessible from the console machine of the node's testbed. First turn the node on using OMF on the console machine. Then use telnet to connect to the correct port exposed by the node's CM (chassis manager).

{{{
username@console:~$ telnet <cm-address> <port>
}}}

To figure out which CM to use, follow these exmaples:
 ||= Node Name =||= CM Address =||
 || '''sdr1'''-s3-lg1.bed.cosmos-lab.org || '''cm'''-s3-lg1.bed.cosmos-lab.org ||
 || '''sdr2'''-md1.bed.cosmos-lab.org || '''cm'''-md1.bed.cosmos-lab.org ||

The port number is determined as follows:
 ||= Node Name =||= Port =||
 || sdr1-... || 10001 ||
 || sdr2-... || 10002 ||

A single CM may be responsible for 2 or more nodes, hence the use of port numbers to differentiate between the nodes themselves.

== Example ==

To connect to the serial console of {{{sdr2-md1.bed.cosmos-lab.org}}}:

First turn on the node:
{{{
username@console:~$ omf tell -a on -t sdr2-md1.bed.cosmos-lab.org
}}}

Then connect to the serial console of {{{sdr2-md1.bed.cosmos-lab.org}}}, which is served by {{{cm-md1.bed.cosmos-lab.org}}} on port {{{10002}}}:

{{{
username@console:~$ telnet cm-md1.bed.cosmos-lab.org 10002
}}}

This will be followed by some messages and finally a 'Connected' greeting indicating the connection was successful.

{{{
Trying 10.109.11.1...
Connected to cm-md1.bed.cosmos-lab.org.
Escape character is '^]'.
Connected to USRP 2974 Serial Console
}}}

At this point, you should be able to login using the username and password you would use when SSH-ing to a node (usually 'root' and no password) and perform the necessary tasks to make the node accessible via SSH again.

== Exit the Serial Console ==

To disconnect from the node's serial console, use {{{ctrl + ]}}} to bring up the telnet prompt:
{{{
telnet>
}}}

Then type {{{q}}} and press {{{Enter}}} to exit.
{{{
telnet> q
Connection closed.
username@console:~$ 
}}}