Tag: WLAN Pi

Programmability is a hot topic these days, but every now and then network engineers require local console access to network infrastructure devices. It is still the primary method for password recovery, staging, troubleshooting, offline image upgrades or learning.

Being able to hug the appliance might give you a warm feeling, but I bet the air conditioning unit blowing cold air usually does not;-) That is where WLAN Pi in Wi-Fi Console mode comes to the rescue.

Wi-Fi Console mode turns the WLAN Pi into a multi-port terminal server and allows you to access all console port connections wirelessly and remotely (or using a wired connection if you prefer).

Nigel Bowden has done all of the heavy lifting. Here is his GitHub repository and documentation. I have recently added support for multiple USB-to-serial adapters and Cisco USB console cables.

All you need is a WLAN Pi with a supported Wi-Fi adapter (if you want to connect wirelessly), USB hub and one or more USB-to-serial adapters or Cisco USB console cables.

It makes an ideal terminal for your home lab – inexpensive, compact and fanless.

Cisco USB console cables

If you are a Cisco customer you may already have a box of spare Cisco USB console cables. Let’s put those to use. You can now connect up to 8 of these cables to your WLAN Pi using a USB hub and access all terminal lines wirelessly – no drivers needed!

Tip: Don’t have a Cisco USB console cable on you? No problem, any standard USB-A to 5-pin mini USB cable would work. 

Note: Using non-standard accessories may void the warranty. Please ask your network infrastructure vendor if you are in doubts.

USB-to-serial adapters

I like using the “noodle” console cables with FTDI chip. They are compact, do not need any additional driver, do not tangle in a bag and you can easily adjust their length.

Tip: Trim the cable to the preferred length and crimp a new RJ-45 connector onto it. The rest of the cable you can crimp another couple of RJ-45 connectors to and use it as an emergency UTP cable. Obviously, it will be more of a “noodle pair” than twisted pair, but you can add one to your adapter bag and it is only a matter of time before it saves the day, trust me;-)

How to use Wi-Fi Console

Make sure your console cables are connected to the WLAN Pi and activate “Wi-Fi Console mode” by going to Menu > Modes > Wi-Fi Console. After the WLAN Pi reboots, all console lines will become accessible wirelessly (or using a wired connection if you prefer).

Connect to the “wifi_console” SSID and telnet to the IP address of the WLAN Pi on the respective TCP port.

USB-to-serial adapters use these ports:

• First USB-to-serial adapter – port 9601
• Second USB-to-serial adapter – port 9602
• …
• Eight USB-to-serial adapter – port 9608

More baud rates are supported. Please check the documentation.

Cisco USB console cables accept connections on these TCP ports:

• First Cisco USB console cable – port 2001
• Second USB-to-serial adapter – port 2002
• …
• Eight USB-to-serial adapter – port 2008

You can mix and match USB-to-serial and Cisco cables on the same WLAN Pi.

Power options for the WLAN Pi

WLAN Pi can be powered using its micro USB connector. There are multiple options available and some work better for certain use cases than others.

A battery pack is the best option if you are using your WLAN Pi as a handheld tool.

For home lab use cases and iperf throughput testing I prefer a gigabit Ethernet PoE splitter with USB type A socket as it is universal and can power the WLAN Pi or even charge your phone. Enterprise switches provide perpetual PoE on the access ports and those will keep your WLAN Pi powered even during and after a switch reload.

Tip: Double-check that the PoE splitter supports gigabit Ethernet before ordering one. This is essential for throughput testing.

Alternatively, use a built-in USB port of your switch or appliance to power the WLAN Pi. Most of these ports are rated at 5 V x 0.5 A = 2.5 Watts. Please do not overload the USB port as this might void the warranty. Personally, I recommend using the WLAN Pi with no Wi-Fi adapter (which draws significant power itself) in this case and connect to the console sessions over a wired connection.

Here is a “Wired Console” WLAN Pi powered by a built-in USB port of a switch and connected to the USB console port of the same switch. The console session is available over the Ethernet interface of the WLAN Pi.

Console access in Classic mode

In fact everything apart from the wireless access is available in the WLAN Pi “Classic mode” and you can use a pre-installed “screen” command to establish console sessions.

Connect to the first USB-to-serial adapter at baud rate of 9600:

screen /dev/ttyUSB0 9600

Replace ttyUSB0 with ttyUSB1 for the second adapter and so on.

Connect to the first Cisco USB console cable:

screen /dev/ttyATM0 9600

Replace ttyATM0 with ttyATM1 for the second cable and so on.

People often joke about quitting the “vi” text editor, but screen is not the most straightforward task either;-) Here are few handy commands for your reference:

Pause screen – Doing this will detach you from the session and you can later resume it by “screen -r”

CTRL+A then CTRL+D

Exit screen – This will take you to the screen command mode. Type “quit” followed by return to exit screen

CTRL+A then type “:”

Exit all screen sessions

CTRL+A followed by \”

With the help of few others, I added some new features to the Front Panel Menu System (FPMS) of the WLAN Pi. I refer to these as “networkinfo”, if you were wondering where the name came from. I am really pleased that most of them actually made it into the official WLAN Pi image and are available to you out of the box. Here is some documentation for you so that you do not have to reverse-engineer the code.

iPhone USB Tethering on WLAN Pi

iPhone USB tethering on the WLAN Pi lets you use your iPhone or iPad as a cellular modem and share the internet connectivity with the WLAN Pi. It also charges your iPhone, which is nice.

You can even take this one step further. Perhaps you have multiple other devices connected to a switch and you need to provide temporary internet connectivity to all of them. That is where the USB Tethering mode comes to the rescue.

Here is my other blog post with step by step instructions on how to enable iPhone tethering on the WLAN Pi.

Public IP Address

“Menu > Network > Public IP Address” shows the public IP address of your WLAN Pi. Country associated to the IP address is displayed along with the AS number and reverse IP address hostname (PTR record) if available.

This feature requires internet connectivity and works with any network interface. I use a publicly available service for this called ifconfig.co.

Reachability

Have you ever wondered if your WLAN Pi had internet connectivity? “Menu > Utils > Reachability” solves exactly this problem. It executes several network tests in parallel and tells you what is reachable and what not.

To name a few of the tests, it pings google.com, tries to browse google.com and looks for “google.com” in the body of the web page (this is to prevent false positives like captive portals), tries to resolve google.com using the primary DNS server (always statically configured to 8.8.8.8 on the WLAN Pi by default), then using secondary and tertiary DNS servers, pings the default gateway and finally arpings the default gateway, which is useful when your default gateway does not respond to a standard ICMP ping request like in the photo below.

The output refreshes every 3 seconds or so and pings and arping display the actual round-trip times.

It takes a couple of seconds to execute after you open “Menu > Utils > Reachability”. It may almost feel like the button was not pressed, but this is normal. Be patient, please.

Default timeouts are set to 2 seconds. If the Pi does not receive any response, it will display “FAIL” for this particular test. If you support satellite or other links with very high latency, you can manually increase the timeout values:

sudo nano ~/BakeBit/Software/Python/scripts/networkinfo/reachability.sh

Reachability works with any network interface and requires a default gateway to be configured – either statically or assigned by DHCP.

Speedtest

“Menu > Utils > Speedtest” utilises the Linux CLI tool developed by Speedtest.net. It takes the output generated by the tool and formats it to fit the OLED screen of the WLAN Pi. Downlink and uplink throughput and the public IP address are shown.

Internet connection is required and it works with any interface. No backend server as such is needed on your network. Ookla and its partners run a network of servers.

I recommend this tool for WAN throughput testing and verification downlink or uplink rate limiting. Please note it is not designed for AP or Wi-Fi performance testing. Use WLAN Pi iperf server connected to your LAN instead.

CDP neighbour detection

Cisco Discovery Protocol (CDP) advertises details and capabilities of network infrastructure devices like APs, routers, switches and IP phones. This feature starts a packet capture on eth0 interface and waits for first the CDP packet to come in. It then parses the data and displays neighbouring device name, model, remote port number and native VLAN.

It only works with eth0 interface of the WLAN Pi and it automatically executes every time eth0 interface changes state to up. It then saves the output to a file located in /tmp/cdpneigh.txt. When you open “Menu > Network > CDP Neighbour”, the neighbour information will be displayed instantly as it has already been cached. Without this capability you would have to wait for up to 60 seconds (default CDP hello timer) before getting any output. Which you might not like;-)

LLDP neighbour detection

Link Layer Discovery Protocol (LLDP) advertises details and capabilities of network infrastructure devices like APs, routers, switches and IP phones and is widely used by vendors. Most of the logic is similar to the CDP tool. It does a packet capture on eth0 and waits for the first LLDP packet to come in. It then parses the output and displays neighbouring device name, model, remote port number and native VLAN.

Currently, it only supports eth0 interface of the WLAN Pi and the script is automatically executed every time eth0 interface goes up. It then buffers the output to a file file located in /tmp/lldpneigh.txt. When you open “Menu > Network > LLDP Neighbour”, the neighbour information has already been captured and will be displayed instantly. Without this capability you would have to wait for up to 30 seconds (default LLDP hello timer) before getting any output.

Eth0 IP Config

“Menu > Network > Eth0” shows all IP details of the built-in eth0 interface including the name and IP address of the DHCP server (unless static IP address has been assigned to eth0), IP address, subnet mask, IP addresses of DNS servers being used (by default primary DNS server is statically configured to 8.8.8.8 on the WLAN Pi), domain name (if configured on the DHCP scope), speed and duplex.

The output automatically refreshes every few seconds or so.

WPA passphrase

Have you ever forgotten the WPA passphrase configured on the WLAN Pi? You can now head over to the “Menu > Network > WPA passphrase” menu and check the current passphrase there.

Wi-Fi Console

This feature allows you to connect to console ports of multiple devices and access them remotely, over a wired network or wirelessly. All you need is a single WLAN Pi, a supported Wi-Fi adapter, USB hub and a few USB-to-serial adapters.

Credit to Nigel Bowden who has done all of the heavy lifting. Here is his GitHub repository and documentation. I have recently added support for up to 8 USB-to-serial adapters and up to 8 Cisco USB console cables. You can mix and match them.

Wi-Fi Console is an ideal terminal server for your home lab – inexpensive, compact and fanless. In my lab I use a standard 7-port hub connected to my WLAN Pi which provides plenty of ports for all my USB-to-serial and USB console adapters. Here is an example:

• RJ-45 console connection to my AP
• USB console to my Wireless LAN Controller
• USB console to my switch

To activate Wi-Fi Console go to “Menu > Modes > Wi-Fi Console”. Connect all adapters and after the WLAN Pi reboots, connect to the “wifi_console” SSID. Finally, telnet to the IP address of your WLAN Pi on respective TCP port to start the console sessions. Port numbers and a few more tips are posted here.

Special thanks

Thanks to the “father” of the WLAN Pi Jerry Olla for keeping things up to date, making sure everyone is in sync and for building the official images. Nigel Bowden played a vital part of this exciting journey and inspired me, thank you sir! Kudos to Adrian Granados for developing some great integrations and tools and thanks to Francois Verges for his Hotspot feature.

There are many other contributors to the WLAN Pi project and they deserve as much kudos as everyone else. Without the right hardware and form factor, there will be no WLAN Pi. Without the Front Panel Menu System, I will not be able to display any output to you.

Thanks to all of you who helped me test and make these features even better.

It has been a pleasure working with you all and meeting you virtually and in person.

Want to get involved?

If you have any ideas on how to improve the WLAN Pi or want to get involved, please do not be shy and reach out to anyone of us, ideally on Twitter. Hashtag #WLANPi and follow @WLANPi.