The invention relates to a method for controlling access to a private network. To a firewall node are updated logical names for mobile nodes allowed to communicate with nodes in the private network. A packet is received to the firewall node from an external network, the packet being addressed to a first node within the private network. The source address is obtained from the packet. Addresses associated with the logical names are obtained from a database node. It is checked whether the source address belongs to the addresses obtained. The packet is admitted to the private network, if the source address belongs to the addresses obtained.