So, I worked at an internet provider up to several years ago, and we were using quite a lot of Cisco routers. Maybe something has radically changed, but I'd be

So, I worked at an internet provider up to several years ago, and we were using quite a lot of Cisco routers. Maybe something has radically changed, but I'd be surprised. Please someone correct me if that's now totally different. A cisco router with a blank config will come up with all interfaces configured "shutdown" and with no passwords set. You access it via a serial port on the front, labeled "Console". It provides a command line almost, but not quite, entirely unlike a unix shell :-) where you enter commands (ping, show routing tables, ..) or configuration statements (config terminal // Interface FastEthernet 0/0 // ip address 10.1.1.1... // no shutdown). If the only thing you do is to give it an ip-adddress on an interface and enable it, it will have a passwordless login via telnet. Every ISP/network department not run by complete imbeciles will have a "standard config" regarding login and passwords: Ours back in the days was a TACACS server for running user authentication, setting access levels for particular users (and automated logins for configuration management) and logging of logins/executed commands. You can also configure access lists that logins are only allowed from specific IP addresses. Probably also have a hardcoded password as fallback when the authentication server isn't reachable, disable the console port for when your router isn't in a locked box, ...