openwrt:allow wan ssh into your wrt

wan_ssh

by default,openwrt do not allow ssh access from wan, here are two method to change that:

1.login into your wrt from a lan host.issue the following command:
iptables -F

the command "flush away" all the firewall rules,including the one that rejects ssh request from wan.
now you can try ssh from anywhere.

aware that the firewall deactivation leads to highly security risk.and after the wrt restarts ,all default firewall configuration comes back.you hava to "flush" the rules once again.

2.add the following lines in /etc/config/firewall :

config rule
        option src              wan
        option dest_port        22
        option target           ACCEPT
        option proto            tcp 

after restart ('reboot' commmand),wrt accept port 22 request (in this case ,ssh request)from wan.

It works. For recent OpenWRT destros, you would need to add ' mark

config rule
        option src              'wan'
        option dest_port        '22'
        option target           'ACCEPT'
        option proto            'tcp' 

12 years later thank you @lynus

thank you @lynus !