Connecting system and pressing tool for a connecting system

A connecting system for connecting a first fluid line (2) to a second fluid line, wherein the connecting system has a connecting sleeve (1) with an open first connecting-sleeve end (3) and an open second connecting sleeve-end (4) connected to the first connecting-sleeve end (3), wherein a first connecting portion (V1) is provided on the connecting sleeve (1), onto which the first fluid line (2) can be pushed in order to connect the first fluid line (2) to the first connecting-sleeve end (3) of the connecting-sleeve (1), and wherein the second connecting-sleeve end (4) comprises a second connecting portion (V2) for connecting to the second fluid line, wherein the first connecting portion (V1) of the connecting sleeve (1) comprises a cylindrical receiving portion (5), wherein a plurality of retaining protrusions (6) that are spaced apart in the circumferential direction and each extend at least along a part of a length of the receiving portion (5) are provided on an outer circumferential surface of the receiving portion (5), and wherein the connecting system comprises a ferrule (13), wherein the ferrule (13) can be arranged on the connecting sleeve (1) such that the ferrule (13) surrounds the receiving portion (5) and such that, in a radial direction between the receiving portion (5) and an inner circumferential surface of the ferrule (13), a receiving space (AR) for receiving an end portion of the first fluid line (2) is formed, wherein the ferrule (13) is configured to be plastically deformed in the circumferential direction in the region between two retaining protrusions (6) by a pressing tool (16) in the radial direction in order to fix the first fluid line (2) to the first connecting portion (V1) in a twistproof manner.