Even when --tmark was used, the iptables code always used '1' for the
mark. This patch corrects the problem.
Previously, it wasn't clear if the tmark should be supplied in
hexadecimal or as an integer. This makes it use hexadecimal, checks
that the input is hexadecimal, and updates the associated
documentation.
This patch also makes --ttl information get passed to the firewall in
a way that matches how other information gets passed. The ttl and
tmark information are passed next to each other in many places and
this patch also makes the order consistent.
If you use the tproxy method with a large subnet (such as 0/0), then
(1) you may not receive UDP packets that sshuttle/tproxy can handle
and (2) you are unable to connect to your machine using an IP that
your computer recognizes as its own.
To resolve those issues, any traffic to an IP that the host knows is
local, does not go through the sshuttle chains.
