A crankcase ventilation for an internal combustion engine with a ventilation conduit which connects the crankcase of the internal combustion engine to an intake duct of the internal combustion engine, as well as a tank ventilation conduit and a connection system for a fluid conduit. The ventilation conduit comprises: a first pipe connector (10), and a second pipe connector (20) with a receiving chamber (24) into which the first pipe connector (10) is insertable, wherein a second groove (22) is formed in the receiving chamber (24), and the first pipe connector (10) has a first groove (12), wherein a compressible retaining ring (40) is inserted into the first groove (12), the compressible retaining ring being engageable with the second groove (22) when the first pipe connector (10) is inserted into the receiving chamber (24), or an expandable retaining ring is inserted into the second groove (22), the expandable retaining ring being engageable with the first groove (12) when the first pipe connector (10) is inserted into the receiving chamber (24).