support IP_LOCAL_PORT_RANGE to improve source port selection
When DNS Shotgun establishes outgoing connections, it can quickly exhaust available source ports. When half of the available port range is depleted, assigning a port takes much longer, which can with the precise timing needed for the traffic replay.
So far, the solution has been to use more IP addresses, but if an insufficient number of them is used, the traffic can still be stalled by this. Since kernel 6.8, the IP_LOCAL_PORT_RANGE option improves the port selection time for the other half of the port range (see the linked blog post).