Cisco 2811 hacking

[mohamed81salah@link.net]

hello all

cable days ago i found ip address from outside my network without users name i try to block this access but the ip keep change and i use and try SSH but this did not stop this attack anly way to stop this attack was via ACL , my question is how this happen , how this attack happen to my 2811 router 

ios Version 15.1(4)M10

c2800nm-advipservicesk9-mz.151-4.M10.bin

[Martin L]

what exactly happened?

Cisco routers are not secure by default (or they used to be).  once you set it up, your must secure it with ACLs, disabling some protocols, restrict access, etc.