Plasma transport at the magnetic axis in toroidal confinement systems is systematically investigated by means of a variational principle for the rate of irreversible entropy production. All the transport coefficients are derived in the banana regime, among them, the bootstrap current and the ion heat conductivity in tokamaks. In the reactor scale, the bootstrap current density may reach 10% of the total plasma current density at the magnetic axis in contrast to the traditional neoclassical results, for which the bootstrap current vanishes at the magnetic axis. The ion heat conductivity has weaker dependence on the magnetic field. We call it Bohm-like diffusion. High temperature is favourable in confinement. The scaling of the transport can be understood in terms of a random walk process in the step of the so-called potato width.