+Darwin and MacOS X
+------------------
+Darwin does not provide a tun(4) driver required for OpenSSH-based
+virtual private networks. The BSD manpage still exists, but the driver
+has been removed in recent releases of Darwin and MacOS X.
+
+Nevertheless, tunnel support is known to work with Darwin 8 and
+MacOS X 10.4 in Point-to-Point (Layer 3) and Ethernet (Layer 2) mode
+using a third party driver. More information is available at:
+ http://www-user.rhrk.uni-kl.de/~nissler/tuntap/
+
+
+Linux
+-----
+
+Some Linux distributions (including Red Hat/Fedora/CentOS) include
+headers and library links in the -devel RPMs rather than the main
+binary RPMs. If you get an error about headers, or complaining about a
+missing prerequisite then you may need to install the equivalent
+development packages. On Redhat based distros these may be openssl-devel,
+zlib-devel and pam-devel, on Debian based distros these may be
+libssl-dev, libz-dev and libpam-dev.
+
+