如何防范SYN---cookies---洪水

CCDD

Jul 29 09:26:21 server270 kernel: possible SYN flooding on port 80. Sending cookies.
Jul 29 10:01:23 server270 kernel: possible SYN flooding on port 80. Sending cookies.
Jul 29 21:35:19 server270 kernel: possible SYN flooding on port 80. Sending cookies.
Jul 29 22:58:59 server270 kernel: possible SYN flooding on port 80. Sending cookies.
Jul 30 05:12:21 server270 kernel: possible SYN flooding on port 80. Sending cookies.
Jul 30 09:29:16 server270 kernel: possible SYN flooding on port 80. Sending cookies.
Jul 30 09:58:45 server270 kernel: possible SYN flooding on port 80. Sending cookies.
Jul 30 23:27:05 server270 kernel: possible SYN flooding on port 80. Sending cookies.
Jul 31 06:45:19 server270 kernel: possible SYN flooding on port 80. Sending cookies.
Jul 31 07:05:01 server270 kernel: possible SYN flooding on port 80. Sending cookies.
Jul 31 07:39:07 server270 kernel: nf_conntrack: table full, dropping packet.
Jul 31 07:43:09 server270 kernel: nf_conntrack: table full, dropping packet.
Jul 31 07:43:39 server270 kernel: nf_conntrack: table full, dropping packet.
Jul 31 07:51:29 server270 kernel: nf_conntrack: table full, dropping packet.
Jul 31 22:20:32 server270 kernel: possible SYN flooding on port 80. Sending cookies.
Aug  1 05:29:21 server270 kernel: possible SYN flooding on port 80. Sending cookies.
Aug  1 07:21:28 server270 kernel: possible SYN flooding on port 80. Sending cookies.
Aug  1 07:47:10 server270 kernel: nf_conntrack: table full, dropping packet.
Aug  1 08:15:08 server270 kernel: nf_conntrack: table full, dropping packet.
Aug  1 08:17:01 server270 kernel: nf_conntrack: table full, dropping packet.
Aug  1 08:17:48 server270 kernel: nf_conntrack: table full, dropping packet.
Aug  1 08:18:44 server270 kernel: nf_conntrack: table full, dropping packet.
Aug  1 08:26:28 server270 kernel: nf_conntrack: table full, dropping packet.
Aug  1 08:27:26 server270 kernel: nf_conntrack: table full, dropping packet.
Aug  1 08:27:54 server270 kernel: nf_conntrack: table full, dropping packet.
Aug  1 08:42:37 server270 kernel: nf_conntrack: table full, dropping packet.
Aug  1 10:02:11 server270 kernel: possible SYN flooding on port 80. Sending cookies.
Aug  1 22:00:00 server270 kernel: possible SYN flooding on port 80. Sending cookies.
Aug  2 08:29:22 server270 kernel: nf_conntrack: table full, dropping packet.
Aug  2 08:29:23 server270 kernel: nf_conntrack: table full, dropping packet.
Aug  2 08:31:05 server270 kernel: nf_conntrack: table full, dropping packet.
Aug  3 03:05:38 server270 kernel: possible SYN flooding on port 80. Sending cookies.
Aug  3 03:06:53 server270 kernel: possible SYN flooding on port 80. Sending cookies.
Aug  3 03:07:58 server270 kernel: possible SYN flooding on port 80. Sending cookies.
Aug  3 03:09:04 server270 kernel: possible SYN flooding on port 80. Sending cookies.
Aug  3 03:10:10 server270 kernel: possible SYN flooding on port 80. Sending cookies.
Aug  3 08:19:24 server270 kernel: possible SYN flooding on port 80. Sending cookies.

domin

nf_conntrack: table full, dropping packet.