USB serial console over IP

Thanks for the nudge bzhou. Here you all go.

1) Setup Nslug as usb terminal server. You'll find this information well documented at http://www.nslu2-linux.org/wiki/SlugOS/HomePage and http://www.nslu2-linux.org/wiki/SlugOS/InstallandTurnupABasicSlugOSSystem so I'll just go over the big picture.
   Flash latest slugos/be
   turnup init and setup networking
   reboot
   put in memstick, fdisk it and make filesystem
   turnup memstick -i /dev/sda1 -t ext2
   reboot verify that /dev/sda1 is mounted as /
    Note: To access the slug, you can easily use ssh.

2) Set the correct date on the slug.

Code:

export TZ=”mytimezone” #Hopefully you know the code to put here. If not, keep it as UTC
date MMDDHHMMYYYY

3) After you've finished with the instructions at the second link, we still need to install a few packages.
Opkg install tzdata

Code:

rm /etc/localtime
ln -s /usr/share/zoneinfo/<yourtimezone> /etc/localtime

opkg install kernel-module-usbserial
opkg install kernel-module-ftdi-sio
opkg install picocom
opkg install screen
opkg install ntp
opkg install syslog-ng

Code:

update-rc.d -f syslog.buffer remove
update-rc.d -f syslog.file remove
update-rc.d -f syslog.network remove
update-rc.d -f syslog remove
update-rc.d syslog-ng defaults

opkg install -force-overwrite logrotate

4) Setup the udev rule for the plug

Code:

nano -w /etc/udev/rules/10-sheevaplug
SYSFS{idProduct}=="9e8f",SYSFS{idVendor}=="9e88",ACTION=="add",RUN+="/sbin/modprobe -q ftdi-sio product=0x9e8f vendor=0x9e88",SYMLINK+"USB[0-1]"
ENV{PRODUCT}=="9e88/9e8f/500",ACTION=="remove",RUN+="/sbin/rmmod ftdi_sio usbserial"

Reload the udev rules

Code:

udevadm control --reload_rules

Plug in the Sheeva to the slug. You should now have /dev/ttyUSB0 and /dev/ttyUSB1 and lsmod should show ftdi_sio and usbserial. If not, go back to step 4 and type in the rules by hand instead of cut and paste.

5) Setup picocom
nano -w /etc/ports.config

Code:

1:jtag:115200 #No, this doesn't work
2:Sheeva:115200

nano -w /usr/bin/consolesh

Code:

#!/bin/sh

done=0

while [ $done -eq 0 ]; do
clear
echo "Welcome to $(hostname)"
echo "Console Server"
echo " Uptime : $(uptime | cut -d, -f1 | cut -d' ' -f4-)"
echo " IP : $( /sbin/ifconfig eth0 | grep 'inet addr' | cut -d: -f2 | cut -d' ' -f1 )"
echo ""
echo "Connected ports:"
ls /dev/ttyUSB* 2>&1 | grep -v no | cut -dB -f2 | while read P; do
D=$(cat /etc/port.config | grep -E "^$(( $P + 1 )):" | cut -d: -f2)
echo " Port $(($P + 1)) : $D"
done
echo ""
echo -n "Please choose a port number to access, or '#' for shell --> "
read PORT
if [ "$PORT" == "" ]; then
exit
fi
if [ "$PORT" == "#" ]; then
echo "Spawning shell, type 'exit' to leave"
sh
else
SPEED=$( cat /etc/port.config | grep -E "^${PORT}:" | cut -d: -f3 )
/usr/bin/serial.sh $PORT $SPEED
fi
done

exit

nano -w /usr/bin/serial.sh

Code:

#!/bin/sh
if [ $# -ne 2 ]; then
echo "syntax: $0 portnumber speed"
exit
fi
PORT=$(( $1 - 1 ))
echo "Escape sequence is Ctrl-A Ctrl-X"
picocom -b $2 -f h -p n -d 8 -r /dev/ttyUSB${PORT}

Make them executable

Code:

chmod +x /usr/bin/consolesh
chmod +x /usr/bin/serial.sh

At this point, you could create a user that has the shell /usr/bin/consolesh, but we are going to be using screen so that we have a scrollback buffer. But just to test, run /usr/bin/consolesh and choose port 2. You should get to the sheeva. If you do, CTRL-A CTRL-X to close picocom, then just hit enter to get out of consolesh.

6) Setup ld.so.conf
nano -w /etc/ld.so.conf

Code:

/opt/lib

then regenerate the cache with

Code:

ldconfig

7) Setup syslog-ng

Change the configuration file

Code:

nano -w /etc/syslog-ng.conf
Replace the entire file with:

options { long_hostnames(off); sync(0); };
source src { pipe("/proc/kmsg");unix-stream("/dev/log"); internal(); };
destination messages { file("/opt/var/log/messages"); };
log { source(src); destination(messages); };

then restart syslog-ng

Code:

/etc/init.d/syslog-ng restart

Setup ntp

Code:

nano -w /etc/ntp/ntp.conf

at the very least change the servers to use pool servers close to you:

Code:

#US Pool
server 0.us.pool.ntp.org
server 1.us.pool.ntp.org
server 2.us.pool.ntp.org

Or if you have an ntp server already setup (like on your Sheeva for instance)

Code:

server <hostname or ip address of sheeva>

9) The final bit is screen. Since it's already installed, just type

Code:

screen /usr/bin/serial.sh 2 115200

And you should be able to get into your connected plug. Detach from the screen with CTRL-A D and you can ssh back into the slug at any time to reconnect with screen -r

At this point you could just reboot the slug. As long as everything was done properly you should now have a working usb terminal server. I suppose you could even add a hub to it, maybe a serial dongle or two and just by adding some more kernel moduels and entries to /etc/port.config and some changes to consolesh have yourself a way to serial console to any device in your garage from your office. Pretty nifty. And it only adds 3.5 watts to the whole setup.