DoS attack against TCP services

[6bone%6bone.informatik.uni-leipzig.de@localhost]

Hello,

it was launched a DoS attack against my server. The attacker opened ssh 
connections from different servers until all sockets are use.

I have stopped the ssh service and terminates all processes. 
Unfortunately, all TCP connections are now in the TIME_WAIT state.

bash-4.3 # netstat -a -n | grep TIME_WAIT | wc -l
    34611

Is there a way to remove it without rebooting the server?

system: netbsd-7.0_BETA

Thank you very much for your efforts

Regards
Uwe