Linux Installation

Uninstalling

sudo /var/lib/zerotier-one/uninstall.sh

If you cannot join networks, check to make sure the tun kernel module is available or tun/tap support is compiled into the kernel.
Make sure your local firewall permits at a minimum UDP traffic to and from local port 9993. If you are installing at a cloud provider like Amazon EC2, ensure that its own firewall settings are not blocking packets on this UDP port.
Depending on your distribution and system configuration, some users may have issues with SELinux preventing the zerotier-one daemon from talking to the network or opening and configuring network tap devices. Right now you're on your own here, though in the future we may have baked-in support for SELinux configuration.
The /proc filesystem must be mounted, though it's rare to find a system where it isn't outside of weird ultra-tiny embedded devices where this probably won't run anyway.
The installer is a self-unpacking shell script and requires /bin/bash and the standard set of shell scripting utilities such as test, cut, etc. If these are missing installation may fail.
If your device makes use of connman to manage network, ensure that NetworkInterfaceBlacklist includes the zt networks to avoid address management conflicts between the daemons
If your device makes use of systemd-networkd to manage network, ensure that the networks are not managed by them to avoid two daemons managing the same network interface