snetmanmon

A simple network manager and monitor for Linux

(C) 2015 - 2018 Alexander Holler

See the file LICENSE for the license.


snetmanmon is a simple alternative to ifupdown, ifplugd, networkmanager,
connman and similiar tools, which all lacked some functionality I wanted.


In particular it makes it possible to not only react on (dis)appearing
interfaces, but also on (dis)appearing IPs and (dis)appearing routes,
besides the possibility to do actions based on the MAC of an interface
too.

Furthermore it's a tool to keep track (logging) of changes in regard
to interfaces, IP addresses and routes on a machine. Something which
becomes more important in times of virtual machines, containers and
software-defined networking (SDN) and which isn't supported by the
tools above.

That means if you want to log the (dis)appearance of interfaces,
IP addresses and routes on your machine, this tool might be your
choice.

But it also gives the possibility to do almost anything else if
a network interface, an IP or route (dis)appears. E.g. if you want to
start a DHCP-client if a WLAN dongle with a MAC a:b:c:d:e:f will be
attached to your system and furthermore you want to start a
NTP-client only if the IP i.j.k.m (or i::*) appears on interface
ethN, this is easy possible to do with snetmanmon too. In short,
if you have a ThingOfInternets (ToI) instead of an IoT,
snetmanmon might be the right tool too.

Have a look at the file snetmanmon.conf.full_example for
documentation and a look at ipv6_rpc.txt for a creative usage example.

Why is it called simple? Because it almost doesn't do any actions
itself. E.g. It doesn't configure network interfaces nor does it
do DHCP by itself, but instead relies on whatever tool the user
prefers to accomplish such actions. This is in line with the old
comcept on Unix systems of "Do One Thing and Do It Well". So,
hopefully, snetmanmon does it well too.

Describing how it works is simple too: snetmanmon listens for rtnetlink
messages generated by the kernel and maintains an internal database of
interfaces, IPs and routes in order to consolidate and extend the
rtnetlink messages it received from the kernel for usage as consistent
events in userspace.


To build snetmanmon, call

	cmake -DCMAKE_BUILD_TYPE=release
	make

Afterwards you just can call it with

	./snetmanmon snetmanmon.conf.simple_example

to test it (no special privileges are needed and nothing else will
be executed).

To build a package for Debian (tested with 8.0 (Jessie)), you need to
install the packages build-essential, cmake, debhelper, libboost-dev,
libboost-regex-dev and libboost-system-dev. Afterwards just call

	dpkg-buildpackage -us -uc

To build a static version (e.g. for older systems where gcc >=4.7 isn't
available) you need the static boost libraries and the static libstdc++
library (e.g. on Fedora you have to install boost-static and
libstdc++-static, on Debian you are getting them with the -dev packages).
To build a statically-linked binary, just use

	LDFLAGS=-static cmake -DCMAKE_BUILD_TYPE=release
	make


If you want to show/use the MTU of routes, please have a look at the
branch named mtu. I haven't merged it, because I think it's of no use for
most people and I want to keep snetmanmon as simple as possible.