In December 2013, The Serval Project commenced a second round of work for the OpenITP (Internet Tools Project) to release software images for the Serval Mesh Extender device and the Serval Mesh app for Android by the end of March 2014.

1. Release Mesh Extender software image
2. Release Serval Mesh Android application

From the grant proposal:

Specifically, we [The Serval Project are requesting OpenITP's support in completing work unit 3, that together with an existing grant under consideration by the NLnet Foundation, and existing work that are have [sic] currently resourced, will allow us to complete stages 1 and 2, and thus release an easy to use and effective Mesh Extender software image, and an integrated version of the Serval Mesh Android application. This will allow the general public to form their own mesh telephony networks over interesting distances using our open-source software.

The work was completed in November 2014, six months later than the contracted date of April 30, 2014. The delay was due to staff absences, more-than-expected technical hitches in the Mesh Extender firmware installation process, and demands of other tasks such as preparation of grant submissions to sustain the Project financially and completion of the following contracts:

• New America Foundation - Contractor Agreement #31A1D0T1CY14 “NAF4”
• New America Foundation - Contractor Agreement #32-OTIUSAID2013 “NAF5”
• New America Foundation - Contractor Agreement #33-OTIUSAID2013 “NAF6”

During December 2014 and January 2015, four pairs of tested and functional Mesh Extender units were prepared to ship to the “Bleeding Edge” supporters of the Speak Freely crowdfunding campaign.

The following work items were performed to satisfy the contract:

• W1. Building Serval DNA for OpenWRT and formal OpenWRT versioning and release procedures
• W2. Improve the “Peer List” screen in the Serval Mesh app for Android
• W3. Improve the “Connect” screen in the Serval Mesh app for Android
• W4. Release Serval Mesh Version 0.92
• W5. Build and install firmware for the Serval Mesh Extender TP-LINK MR3020 prototype

The following supplemental work items demonstrate fulfilment:

• W6. Ship four working pairs of Mesh Extenders
• W7. Support our Mesh Extender early adopters

<BOOKMARK:W1>

The Mesh Extender firmware is an OpenWRT image, so during February and March 2014, formal OpenWRT build and release support was added to Serval DNA:

• An official Serval OpenWRT feed repository was created and its branching policy established and documented, with explicit support for building Mesh Extender firmware compatible with any official release of Serval Mesh app for Android.

• The new sp-openwrt-release script was added to the serval-tools repository, to automate the process of releasing Serval packages for OpenWRT instead of developers making manual changes to the Serval OpenWRT feed repository.

• Detailed instructions for building, developing and releasing Serval DNA for OpenWRT were written and tested.

• The Serval DNA development Makefile was introduced to support an OpenWRT edit-compile-test development cycle using the local working copy of Serval DNA instead of its GitHub repository.

• OpenWRT build and release steps were added to the Serval Mesh release procedure, to ensure that the OpenWRT platform is not neglected.

<BOOKMARK:W2>

The “Peer List” screen (activity) of the Serval Mesh app for Android was unresponsive and sometimes failed to update, which made it difficult for users to spot the presence of Mesh Extender access points.

From January to March 2014, we changed the “Peer List” activity's back-end interface with Serval DNA. Instead of synchronous (blocking) calls through the JNI interface, a new, asynchronous Java API was developed for MDP network client processes, and the connect activity was altered to send and receive Distributed Numbering Architechure (DNA) queries and replies without blocking.

We used this opportunity to improve the software architecture by adding a Java API layer to the Serval DNA component itself so that other applications can easily embed it and communicate with it, independently of the Serval Mesh application. This had the immediate advantage of bringing the new Java API code under the scope of the Serval DNA testing framework. New test cases were written to specify the semantics and contracts of the new Java API and to prevent regressions. The existing Java code in the Serval Mesh application for communicating with Serval DNA was replaced by the new Java API, which effectively increased the test coverage of the Serval Mesh app for Android.

• the commits batphone ff2303c, batphone 26673ef, serval-dna 99fb8b6, serval-dna 46ef40c and serval-dna 63db7b4 moved the existing Java API from the Batphone repository to the Serval DNA repository
• commit serval-dna 20494a9 created the new Java API for MDP clients
• commits batphone 0e21c99 and batphone 6e71aea upgraded the “Peer List” activity and all other places peer details are displayed to use asynchronous MDP instead of synchronous JNI

<BOOKMARK:W3>

The “Connect” screen (activity) of the Serval Mesh app for Android was designed for experts, and was not very usable.

In order to make it easy for users to connect to Mesh Extenders, we redesigned and simplified the “Connect” activity:

• the “Auto Cycle” checkbox was removed, leaving only the “Enable Services” checkbox
• the list of all Android Wi-Fi networks was replaced by a single “Wi-Fi” checkbox and a settings icon that opens the Android “Wi-Fi Settings” activity where the user can select from a list of available access points
• the Personal Hotspot option was placed on a “Portable Wi-Fi hotspot” checkbox and a settings icon that opens the Android “Personal Wi-Fi Hotspot Settings” activity
• the Ad Hoc Wi-Fi option was placed on an “Ad Hoc Mesh” checkbox which is initially greyed out (unavailable).

During February and March 2014, we improved the “Connect” activity:

• commit batphone 21576d3 contains the bulk of the changes
• commit batphone a137c12 added the “Settings” icons to the options
• commit batphone 1464c99 relegated the HERE BE DRAGONS dialog to behind the “Ad Hoc Mesh” option
• commit batphone 5680b64 tweaked the wording of the informative texts on the options to help users understand their options and give the UI more polish

Pressing the “Ad Hoc Mesh” label the first time initiates the process of probing for Ad Hoc capability, and pops up the HERE BE DRAGONS! warning. If the user chooses to Test, then the Serval Mesh application will attempt to use Super-User privilege to re-install the system Wi-Fi driver, which will pop up a dialog asking if the user will grant Super User privilege to Serval Mesh. By relegating these scary warnings and pop-ups behind the “Ad Hoc Mesh” button, we were able to remove them from the app's first-time start wizard, which was a significant obstacle to adoption.

The new “Connect” screen is much simpler than its predecessor, yet still requires more usability work. Users still need to know that they have to connect to mesh.servalproject.org in order to connect to a Mesh Extender. However, the design of the new “Connect” screen was directed towards eventually adding an extra row labelled “Mesh Extender”, which would be greyed out (unavailable) unless one or more Mesh Extender access points were within range. Checking the “Mesh Extender” option would automatically enable Wi-Fi and associate to the mesh.servalproject.org access point. We did not implement this because there are usability and implementation issues yet to be resolved, such as:

• the presence of Mesh Extenders cannot be detected unless Wi-Fi is first activated (Wi-Fi Direct might help solve this problem)
• if Wi-Fi is already activated, associating to a Mesh Extender would disconnect from any network the user had already connected to, which violates the UX principle of “no unpleasant surprises”
• we want to garner feedback on the new “Connect” screen before proceeding to change it

<BOOKMARK:W4>

The Serval Mesh Version 0.92 encapsulated the improvements made in W2 and W3, as well as many bug fixes, performance and stability improvements. The Release Notes list all the changes and known issues, and acknowledge the funding support of OpenITP.

The 0.92 release process lasted eight months from March to October 2014:

• on March 1, the first release candidate 0.92-RC1 was created
• on March 24, the second release candidate 0.92-RC2 was created
• on March 24, a message was sent to the Serval Project Developers list encouraging Beta testers
• on July 28, the third release candidate 0.92-RC3 was created and announced
• on August 15, the fourth release candidate 0.92-RC4 was created and announced
• on October 1, the fifth release candidate 0.92-RC5 was created and announced
• on October 27, the final release 0.92 was created and announced

<BOOKMARK:W5>

From July to November 2014, scripts and documentation for installing the Mesh Extender firmware on an TP-LINK MR2030 from scratch were developed and committed to the new Mesh Extender Builder GitHub repository. This work was complicated by several technical issues:

• The develop-test cycle was significantly slowed by the need to re-flash and reboot a Mesh Extender on every single change.

• The Sandisk USB flash pen drives that we had purchased to use in the Mesh Extender were defective: after some number of disconnects without a proper sync and unmount (ie, on every Mesh Extender hard reset), they would permanently revert to read-only mode. We contacted Sandisk, who confirmed they were aware of the issue but did not intend to correct it.

• The OpenWRT image produced by W1 turned out to be slightly too big to fit into the MR2030 flash memory, so the serval-dna package had to be excluded from the core image and built as a module instead.

• The original RFD-900 radio module serial flash loader utility was a Python script, which slowed down the MR3020 boot process and required the OpenWRT image to include the Python interpreter, so we developed new serial flash loader in C which reduced the boot time and allowed us to shrink the OpenWRT image by removing Python.

• The RFD-900 radio module could boot into different serial settings, making detection of the module's firmware version slow and unreliable, so we decided to always upload the radio firmware on every boot.

• The Auto Upgrade feature could not be tested while any other Serval Mesh nodes were active within Wi-Fi range, because upgrade images stored on other devices would interfere with the test.

The repository's README.md contains instructions for creating a USB flash drive containing the Mesh Extender software image:

• STEP 1. On a Linux workstation, the user runs the make_image script, which:
  • downloads the OpenWRT 12.09 (“Attitude Adjustment”) image builder tarball for the MR3020 target,
  • uses the OpenWRT image builder to compile a working, generic Mesh Extender firmware image from source,
  • inserts the image files into the generic firmware image, which includes all the configuration and settings needed to boot a Mesh Extender, plus the radio module serial flash loader executable binary and radio firmware blob.

The generic OpenWRT image builder does not build Serval DNA. Instead, the pre-built servald executable binary is contained in the repository. The make_image script could be improved to compile Serval DNA from source during STEP 1, but limited time and budget did not permit further refinement.

• STEP 2. The user runs the gather-image-files script, which:
  • downloads the latest Serval Mesh release APK from the Serval Project server,
  • downloads the source code for all Serval software components from GitHub and rolls them into tarballs, which will be copied to the Mesh Extender to provide off-line access to all technical documentation, offer transparent evidence of software validity, and to comply with GPL licensing terms
  • collects some OpenWRT packages that were built as modules, and not included in the main firmware image
  • assembles a staged directory that will be copied verbatim to the USB flash drive
  • assembles an upgrade file, serval.up, that will be copied verbatime to the USB flash drive

• STEP 3. The user connects the target Mesh Extender unit to the workstation by Ethernet cable and flashes the new firmware image to it using one of two options:
  1. If the unit is virgin (factory settings; ie, never had the Mesh Extender firmware installed before) then the user runs the flash-virgin-mr3020 script, which uploads the firmware image via HTTP to the IP address 192.168.0.254 (the MR3020 default factory IP address), then issues another HTTP command to initiate the flash upgrade.
  2. If the unit has already been flashed at least once with the Mesh Extender firmware, then the user runs the reflash-mesh-extender script with the IP address of the unit as its first argument, which uploads the firmware image via SSH to the given IP address, then executes the sysupgrade command on the unit using SSH.

After STEP 3 the Mesh Extender unit will reboot, and will be running the new firmware kernel. The following steps install all the staged files to the Mesh Extender.

• STEP 4. The user inserts a USB flash drive into the workstation and runs the partition-memory-stick.sh script, which partitions the USB flash drive (erasing existing partitions). The user must then remove and re-insert the USB flash drive to ensure that the workstation detects the new partitions. If re-using a USB flash drive from a previous run, then this step can be omitted, since it will already be partitioned correctly.

• STEP 5. The user runs the populate-memory-stick script, which formats the new partitions of the USB flash drive and copies the staged directory and Serval DNA configuration file to their respective partitions. It also creates the NOROOT file in the root of one of the partitions.

The user may then remove the USB flash drive from the workstation, insert it in the Mesh Extender unit, and power it up. The Mesh Extender will automatically upgrade itself from the contents of the USB flash drive then reboot. The Mesh Extender unit is now fully functional.

The presence of the NOROOT file in its corresponding USB flash partition prevents the Mesh Extender from accepting logins via SSH, for security reasons. Anybody with physical access to the unit can re-enable SSH logins by extracting the USB flash drive, inserting it in a workstation, removing the NOROOT file, re-inserting it in the Mesh Extender unit, and powering up the unit. The unit will re-create the NOROOT file and accept SSH logins until its next reboot, so enabling SSH logins by this method is not permanent.

The user may repeat STEP 3, STEP 4 and STEP 5 as often as desired to flash new Mesh Extender units from the same firmware image and create new USB flash drives for them.

<BOOKMARK:W6>

The Speak Freely crowdfunding campaign, which ran from July to September 2013, raised 13,465 USD for Mesh Extender development, which included donations from four “True Believer” supporters who are now credited in the Serval Mesh app, and from four “Bleeding Edge” supporters, to each of whom we will give a pair of working Mesh Extender MR3020 prototype units. As a bonus for late delivery, we will also give them each a pair of Huawei IDEOS X1 u8180 phones with Serval Mesh Version 0.92 pre-installed and tested in conjunction with the pair of Mesh Extender units.

During December 2014 and January 2015, we assembled and tested four pairs of Mesh Extender prototype units. This was complicated by technical difficulties such as defective RFD-900 radio modules, serial cable solder joint failures caused by repeated extraction and insertion into the 3D-printed case, and defective Sandisk USB flash drive units. Once these issues were overcome, the units performed correctly. The units and phones were shipped in January 2015.

<BOOKMARK:W7>

The Mesh Extender is still very much in prototype stage, and we are now focussed on getting as many as possible into the hands of early adopters. The Serval Project Developers group is our primary means for receiving feedback and providing technical support.

The following message threads reveal the presence of a few Mesh Extender early adopters:

• November 5, 2014 – mesh extender firmware
• October 31, 2014 – mesh extender firmware update
• October 24, 2014 – mesh extender firmware
• October 2, 2014 – mesh-extender-builder
• June 26, 2014 – clever/foolish mesh extender ideas
• June 4, 2014 – Mesh Extender 400 MHz
• October 30, 2013 – alternative mesh extender config