I wanted to document some steps that I took to get Connman working for setting up a WiFI AP. Connman terminology for this is “tethering”. All of this was done on a recent (Feb2016) Debian Jessie distro with the 4.1.x TI kernel.
- There is an issue with the systemd connman.service unit file. Connman needs to be able to dynamically load kernel modules in order for tethering to work. The systemd unit file lacks the CAP_SYS_MODULE capability in the CapabilityBoundingSet property. The proper setting should be:
CapabilityBoundingSet=CAP_KILL CAP_NET_ADMIN CAP_NET_BIND_SERVICE CAP_NET_RAW CAP_SYS_TIME CAP_SYS_MODULE
I first attempted to add a systemd drop-in to merge this into the distros connman.service, but alas, also ran into systemd issue 1221 (https://github.com/systemd/systemd/issues/1221). Apparently this systemd issue was fixed after release 226. Currently, RCN Debian images run systemd 215. So, you will have to directly modify /lib/systemd/system/connman.service to correct this capability deficiency.
I have posted a bug report to the Connman mail list, and a patch has been committed to Connman mainline to fix this missing capability (commit 9e96310).
Stop and disable dnsmasq service. dnsmasq is being used for DHCP on the usb gadget. dnsmasq apparently conflicts with Connman’s internal DHCP.
I renamed /etc/dnsmasq.d/usb0-dhcp to /etc/dnsmasq.d/usb0-dhcp~ to disable boot time setup being performed by /opt/scripts/boot/autoconfigure_usb0.sh
I renamed /etc/network/interfaces to /etc/network/interfaces.org to avoid any conflicts and confusion between Connman and legacy ifup/ifdown and test that Connman can truely deal with all network setup without having to resort to any legacy tools.
After these fixes, I can now successfully setup a WiFI AP using
connmanctl. Traffic on the AP will have internet traffic routed to the ethernet interface. Client STAs connected to the AP will have DHCP allocated IP addresses (typically on the 192.168.0.1/24 network).
connmanctl enable wifi
connmanctl tether wifi on
Note that I can also setup a usb gadget tether using similar
connmanctl enable gadget
connmanctl tether gadget on
A client connected to the usb gadget will also have a DHCP allocated IP address (again typically on the 192.168.0.1/24 network). You may need to re-plug the USB cable in order to have an IP address allocated after you turn on the tether.
So, all of this avoids the
create_ap hackery and the necessity to run dnsmasq for the usb ethernet gadget. Unfortunately, I see no way to use this method to allocate a static IP address on the usb gadget. Reading the Connman mail list, I doubt defining a static IP for the usb gadget would ever be supported as in general there is no way to guarantee that wouldn’t be a conflict with the static IP…or at least that’s the way I read the discussion. But, the BBB does show up via mDNS on the client (in this case, my Linux laptop). Both the BBB web site and the “workstation” show up via Avahi Discovery browser. And I can ssh to the BBB via .local. So, maybe we don’t necessarily need a static IP to supporting “connecting” to the BBB from usb clients?
This all seems to be encouraging as a possible path to addressing the “requirements” that JasonK enumerated in this thread: https://groups.google.com/forum/#!category-topic/beagleboard/v4_A2x1I5gs