kernel: Limiting icmp unreach response from 299 to 200 packets/sec

/var/log/messages
Oct 15 09:38:32 machine kernel: Limiting icmp unreach response from 299 to 200 packets/sec

當出現以上訊息時，可能是RST攻擊，可以設定以下參數(預設為0)。

sysctl -w net.inet.tcp.blackhole=2
sysctl -w net.inet.udp.blackhole=1

然後在/etc/sysctl.conf加入
net.inet.tcp.blackhole=2

net.inet.udp.blackhole=1

mail relay

#/etc/rc.conf加入
sendmail_enable="YES"

#新增 mail relay
cd /etc/mail/
ee access
#格式 192.168.1.1   RELAY
make
make restart