The invention concerns an external well packer (4, 4′, 4″) for a pipe string (2), and also a method of leading at least one line (18) seamlessly past at least one packer (4, 4′, 4″) along the pipe string (2). What is characteristic of the packer (4, 4′, 4″) is that it consists of a continuous inner packer ring (8) and a separate and continuous outer packer ring (10), which in the operating position encloses the inner packer ring (8) in a pressure tight manner. The fitting surface of at least one of the packer rings (8, 10) is provided with at least one through-going line slot (16, 16′), which in the operating position encloses a line (18) in a pressure tight manner. This allows continuous lines (18) to be stretched out past several such packers (4, 4′, 4″).