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Access serial console of another device thru Checkpoint Appliance USB port


I had the need to configure a new Cisco 3750 switch at a remote site with minimal hands-on help.   I had remote ssh access to an R80.20 3100 appliance on site and wondered if could use the 3750 console cable plugged into the 3100 to access the 3750 switch console.

I arranged for the mini-USB end of the 3750 console cable to be plugged into the Cisco 3750 mini-USB console port and the other end to be plugged into the Checkpoint 3100 appliance Type-A USB  port.

Running the dmesg command in expert mode I could see that the GAIA kernel had created a serial device file after the cable was connected:

[Expert@sta-fw01:0]# dmesg | tail -30
usb 1-1.2: new full speed USB device using ehci_hcd and address 3 usb 1-1.2: configuration #1 chosen from 1 choice drivers/usb/class/cdc-acm.c: This device cannot do calls on its own. It is no modem. cdc_acm 1-1.2:1.0: ttyACM0: USB ACM device usbcore: registered new driver cdc_acm drivers/usb/class/cdc-acm.c: v0.25:USB Abstract Control Model driver for USB modems and ISDN adapters

Using the cat command I could see that I had good serial connectivity to the switch:

[Expert@sta-fw01:0]# cat < /dev/ttyACM0 
Apr  3 01:26:06.726: %USB_CON

Now I just needed to find a terminal emulation program in GAIA that would give me an interactive connection over the serial port to the switch.   I searched for tip, minicom and several others to no avail, and then I discovered that GAIA comes with the picocom terminal emulation program installed.

I just ran the command: picocom /dev/ttyACM0  and bingo I had an interactive connection over the USB serial cable to the switch:


[Expert@sta-fw01:0]# picocom /dev/ttyACM0 
picocom v2.1
port is        : /dev/ttyACM0
flowcontrol    : none
baudrate is    : 9600
parity is      : none
databits are   : 8
stopbits are   : 1
escape is      : C-a
local echo is  : no
noinit is      : no
noreset is     : no
nolock is      : no
send_cmd is    : sz -vv
receive_cmd is : rz -vv -E
imap is        : 
omap is        : 
emap is        : crcrlf,delbs,

Type [C-a] [C-h] to see available commands

Terminal ready

Apr  3 01:42:26.784: %LINK-3-U
Switch> en
Switch# show ver | inc Cisco
Cisco IOS Software, C3750E Software (C3750E-UNIVERSALK9-M), Version 15.2(1)E2, RELEASE SOFTWARE (fc1)

 Once connected via picocom, Ctrl-a Ctrl-h displays a helpful list of escape sequences like Ctrl-a Ctrl-x to end the session:


*** Picocom commands (all prefixed by [C-a])

*** [C-x] : Exit picocom
*** [C-q] : Exit without reseting serial port
*** [C-b] : Set baudrate
*** [C-u] : Increase baudrate (baud-up)
*** [C-d] : Decrease baudrate (baud-down)
*** [C-i] : Change number of databits
*** [C-j] : Change number of stopbits
*** [C-f] : Change flow-control mode
*** [C-y] : Change parity mode
*** [C-p] : Pulse DTR
*** [C-t] : Toggle DTR
*** [C-|] : Send break
*** [C-c] : Toggle local echo
*** [C-s] : Send file
*** [C-r] : Receive file
*** [C-v] : Show port settings 


Anyways, I thought others may find this helpful for remote configuration of devices with a USB console port in a pinch. 

The same method could be used to remotely configure a Checkpoint Appliance manually using isomorphic USB GAIA installation and the config_system command for the first time configuration.


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