Usage: ss-nat [-opc] [options]
       ss-nat -f

Valid options are:

    -s <server_ip>          hostname (requires dig) or ip address of shadowsocks remote server
    -l <local_port>         port number of shadowsocks local server
    -S <server_ip>          hostname (requires dig) or ip address of shadowsocks remote UDP server
    -L <local_port>         port number of shadowsocks local UDP server
    -i <ip_list_file>       a file content is bypassed ip list
    -I <interface>          lan interface of nat, default: eth0
    -a <lan_ips>            lan ip of access control, need a prefix to
    define access control mode
    -b <wan_ips>            wan ip of will be bypassed
    -w <wan_ips>            wan ip of will be forwarded
    -c <filename>		read configuration from /etc/shadowsocks-libev/filename.json
    other options will overload this config file
    -e <extra_options>      extra options for iptables
    -o                      apply the rules to the OUTPUT chain
    -p                      apply the rules to the PREROUTING chain 
    -u                      enable udprelay mode, TPROXY is required
    -U                      enable udprelay mode, using different IP
    and ports for TCP and UDP
    -r                      change default dns server: 8.8.8.8 and 8.8.4.4
                            (requires resolvconf.service)
    -f                      flush the rules
    -h                      show this help message and exit

    ss-nat -f -I eth0 -r
    ss-nat -s $serverip -l $serverport -I eth0 -u -o -r