Enric,
I think your problem may be related to ConnMan. ConnMan is a network manager that is installed on the Jessie test images. It manages your network connections, including eth. Any settings you have in /etc/network/interfaces is overriden by ConnMan, and thus this is why you see a DHCP assigned address rather than the static address configured in /etc/network/interfaces when you reboot.
You can disable ConnMan (not recommended), tell ConnMan to not manage eth0 on your behalf and manage things yourself (again, not recommended), or use ConnMan to setup a static IP address. Using ConnMan to setup a static IP address will be “persistent”, that is it will survive reboots. This is pretty simple:
First, determine the “service” name of your ethernet:
connmanctl services
Using the appropriate ethernet service, tell connman to setup a static IP address for that service:
sudo connmanctl config --ipv4 manual <ip_addr> --nameservers <dns_server>
You will need to pick an IP address compatible with your network and router.
For example:
$ connmanctl services
*AO Wired ethernet_d05fb8ed4f78_cable
$ sudo connmanctl config ethernet_d05fb8ed4f78_cable --ipv4 manual 10.0.1.100 255.255.255.0 10.0.1.1 --nameservers 8.8.8.8
You should then see the new address using the “ip” command:
$ ip addr show dev eth0
2: eth0: <BROADCAST,MULTICAST,DYNAMIC,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP group default qlen 1000
link/ether d0:5f:b8:ed:4f:78 brd ff:ff:ff:ff:ff:ff
inet 10.0.1.100/24 brd 10.0.1.255 scope global eth0
valid_lft forever preferred_lft forever
inet6 fe80::d25f:b8ff:feed:4f78/64 scope link
valid_lft forever preferred_lft forever
You should now also be able to “ping” an address such as “google.com”.
You can revert back to a DHCP configuration simply as follows:
$ sudo connmanctl config ethernet_d05fb8ed4f78_cable --ipv4 dhcp
It would be best if you have a FTDI serial cable so you can see what is going on at the console in case something goes wrong. Actually, it would be best to issues these commands from the console rather than ssh’ing.
Hope this helps
ba