Port 22 is blocked as a safety mechanism. In a case where nebula is
started before sshd, a system may be rendered unreachable if nebula
is holding the system ssh port and there is no other connectivity.
This commit enforces the restriction, which could previously be worked
around by listening on an IPv6 address, e.g. "[::]:22".
* Remove unused (*udpConn).Read method
* Align linux UDP performance optimizations with configuration
While attempting to run nebula on an older Synology NAS, it became
apparent that some of the performance optimizations effectively
block support for older kernels. The recvmmsg syscall was added in
linux kernel 2.6.33, and the Synology DS212j (among other models)
is pinned to 2.6.32.12.
Similarly, SO_REUSEPORT was added to the kernel in the 3.9 cycle.
While this option has been backported into some older trees, it
is also missing from the Synology kernel.
This commit allows nebula to be run on linux devices with older
kernels if the config options are set up with a single listener
and a UDP batch size of 1.
This commit adds support for Nebula to be started without creating
a tun device. A node started in this mode still has a full "control
plane", but no effective "data plane". Its use is suited to a
lighthouse that has no need to partake in the mesh VPN.
Consequently, creation of the tun device is the only reason nebula
neesd to be started with elevated privileged, so this example
lighthouse can also be run as a non-root user.
forfuncsake