Since it's only Layer 7; just install something such as DDOS Deflate or null route the IP Range.

To null route the IP:

route add -host 222.186.129.X reject
ip route get 222.186.129.x

RTNETLINK answers: Network is unreachable
To null route the whole subnet:

route add -net 222.186.0/24 gw lo
Or to install DDOS Deflate:

chmod 0700
(Uninstall) ->

chmod 0700 uninstall.ddos
If the attack is still to big to handle I recommend contacting your ISP; however another option is to get a reverse proxy which has DDOS Protection from Layer 7 attacks such as (Quite cheap soloution)