启动ip转法功能

这种方法无需重启:

[[email protected] ~]# cat /proc/sys/net/ipv4/ip_forward
0
[[email protected] ~]# sysctl -w net.ipv4.ip_forward=1
net.ipv4.ip_forward = 1
[[email protected] ~]# cat /proc/sys/net/ipv4/ip_forward
1

[[email protected] ~]# sysctl -p /etc/sysctl.conf
net.ipv4.ip_forward = 0
net.ipv4.conf.default.rp_filter = 1
net.ipv4.conf.default.accept_source_route = 0
kernel.sysrq = 0
kernel.core_uses_pid = 1
net.ipv4.tcp_syncookies = 1
kernel.msgmnb = 65536
kernel.msgmax = 65536
kernel.shmmax = 68719476736
kernel.shmall = 4294967296