Software Distribution Platform: Difference between revisions

Revision as of 06:21, 16 February 2005

Conception for a software distribution platform for a distributed network of WRT54GS nodes.

The identified requirements are as follows:

dynamic network of homogenous nodes (no privileged nodes)
- nodes may be turned off or disconnected for any period of time from the remaining network
- network may be split for any period of time
- nodes may be added at any time
no centralized datastore
- avoids single point of failure
- less administration
robust and reliable updates
- allow updates even with broken routing
- cross-compatible beginning with version 1.0.0 (e.g. allow update of a node running 1.0.0 with version 1.5.99)
broken, untrustworthy and malicious nodes must not be able to install unwanted software (optional: not interfere with the updating process)
trustworthy developer team and CA
all nodes should have the same software version running most of the time (ideally every second)
implementation must fit into limited hardware (e.g. 32MB RAM + 8MB flash (optional: WRT54G))

The ideas to meet those requirements:

discovery mechanism for newer versions on neighbours
- push and/or pull
- broadcast(push) and/or query
if newer version is available, fetch it (e.g. over existing TFTP)
infection based distribution mechanism
- obtain code from neighbour
- new version can be injected on any connected node
- distributed step by step to each connected node
notification and update protocol never changes after 1.0.0 is released
sign each software update package with a CA key
CA public key is preinstalled with the base system on every node to check authenticity of new files
synchronize system clocks over NTP (using broadcast UDP port 123) or a simpler non-standard protocol with neighbours
- guaranteeing similar system times for software switches and logs
include software starting time (and end time for experimental software) in each update package
coordinated switch over to new version if system_time > start_time
coordinated switch-back to non-experimental version if system_time > end_time

@@ Line 30: / Line 30: @@
 * sign each software update package with a CA key
 * CA public key is preinstalled with the base system on every node to check authenticity of new files
-* synchronize system clocks over NTP (using UDP port 123) with neighbours
+* synchronize system clocks over NTP (using broadcast UDP port 123) or a simpler  non-standard protocol with neighbours
-** guaranteeing similar system times
+** guaranteeing similar system times for software switches and logs
 * include software starting time (and end time for experimental software) in each update package
 * coordinated switch over to new version if system_time > start_time