This change makes the subnets with the most specific port ranges come
before subnets with larger, least specific, port ranges. Before this
change subnets with smaller swidth would always come first and only for
subnets with the same width would the size of the port range be
considered.

Example:
188.0.0.0/8 -x 0.0.0.0/0:443
Before: 188.0.0.0/8 would come first meaning that all ports would be
routed through the VPN for the subnet 188.0.0.0/8
After: 0.0.0.0/0:443 comes first, meaning that port 443 will be
excluded for all subnets, including 188.0.0.0/8. All other ports of
188.0.0.0/8 will be routed.

* Adds support for tunneling specific port ranges

This set of changes implements the ability of specifying a port or port
range for an IP or subnet to only tunnel those ports for that subnet.
Also supports excluding a port or port range for a given IP or subnet.

When, for a given subnet, there are intercepting ranges being added and
excluded, the most specific, i.e., smaller range, takes precedence. In
case of a tie the exclusion wins.

For different subnets, the most specific, i.e., largest swidth, takes
precedence independent of any eventual port ranges.

Examples:
Tunnels all traffic to the 188.0.0.0/8 subnet except those to port 443.
```
sshuttle -r <server> 188.0.0.0/8 -x 188.0.0.0/8:443
```

Only tunnels traffic to port 80 of the 188.0.0.0/8 subnet.
```
sshuttle -r <server> 188.0.0.0/8:80
```

Tunnels traffic to the 188.0.0.0/8 subnet and the port range that goes
from 80 to 89.
```
sshuttle -r <server> 188.0.0.0/8:80-89 -x 188.0.0.0/8:80-90
```

* Allow subnets to be specified with domain names

Simplifies the implementation of address parsing by using
socket.getaddrinfo(), which can handle domain resolution, IPv4 and IPv6
addresses. This was proposed and mostly implemented by @DavidBuchanan314
in #146.
Signed-off-by: David Buchanan <DavidBuchanan314@users.noreply.github.com>
Signed-off-by: João Vieira <vieira@yubo.be>

* Also use getaddrinfo for parsing listen addr:port

* Fixes tests for tunneling a port range

* Updates documentation to include port/port range

Adds some examples with subnet:port and subnet:port-port.
Also clarifies the versions of Python supported on the server while
maintaining the recommendation for Python 2.7, 3.5 or later.
Mentions support for pfSense.

* In Py2 only named arguments may follow *expression

Fixes issue in Python 2.7 where *expression may only be followed by
named arguments.

* Use right regex to extract ip4/6, mask and ports

* Tests for parse_subnetport

netstat outputs some headers in BSD (that the Linux version does not)
that are not tabular and were breaking our 'split line into columns
and get nth column' logic. We now skip such headers.

Should fix #141.

There was runtime failure on UDP or DNS processing, because "socket" was redefined to PyXAPI's socket_ext in tproxy.py, but still was plain Python's socket in client.py
Fixed https://github.com/sshuttle/sshuttle/issues/134 for me

`netstat` has been deprecated for some time and some distros might
start shipping without it in the near future. This commit adds support
for `ip route` and uses it when available.

Sponsored-by: rsync.net

PfSense is based on FreeBSD and its pf is pretty close to the one
FreeBSD ships, however some structures have different fields and two
offsets had to be fixed.

We set it to true when we enable pf, but do not set it back to False
after disabling. When using IPv4 and IPv6 we end up trying to disable
twice which procudes an error while undoing changes in FreeBSD 11.

Added missing full stops and explain that Type=notify is needed in the
systemd service unit.

Some tests and documentation for the systemd notification feature.
Also fixes some corner case issues detected while writing the tests.

As it is only required to run the tests move pytest-runner from
setup_requires to tests_require as suggested by @jonathanunderwood
on #115.

These changes introduce support for sdnotify allowing sshuttle to notify
systemd when it finishes connecting to the server and installing
firewall rules, and is ready to tunnel requests.

This should fix an issue introduced in #117 where when no subnets are
given via file (-s file) the variable is None instead of an empty list
and the concatenation with the subnets given as positional parameters
fails.

By just splitting at spaces, multi-word arguments are torn apart even if
quoted. In case of custom ssh-cmd, this makes it practically impossible
to set certian options through `ssh -o`.
shlex splits arguments like a shell and e.g. respects quotes.

This should fix #116. Handling this while still having the positional
arguments and -s both write to the same list turned out to be more
complicated than it's worth so each writes to their own variable and we
merge them at the end.

requirements.rst: Fix mistakes

Closes #111.

IPv6 support for OSX and BSDs