Learning by Doing: CISCO Certified Network ... - SCN Research

eserved for CISCO routers. Yup…knowing which type of equipment is in use is
beneficial to hackers. Most CISCO network administrators have it “drummed in
their heads” that there are only 5 vty lines available (and, for you people studying
for the CCNA there are only 5) but, enterprise versions of routers have up to 1000
or so vty lines possible. Knowing a CISCO device exists and knowing most
admins do not know about those “upper” vty lines creates security holes. For
example, if I open up 6 simultaneous vty session with Telnet to a CISCO
device…
Session 1>open vty 0 > password requested
Session 2>open vty 1 > password requested
Session 3>open vty 2 > password requested
Session 4>open vty 3 > password requested
Session 5>open vty 4 > password requested
Session 6>open vty 5 > no password required=keys to the kingdom!
To find out how many vty lines you have type this:
Router>en
Router#config t
RouterA(config)#line vty 0 ?
3. Want to keep people from walking up to your session and making changes? Put a
password on it. Try to figure out how to do that.
So What Have I Learned Here?
In this lab you have learned how to set up the basics on a router. You will be using this
information pretty much for every lab left in this book. After a while this will become
automatic to you. In the next lab we will put this to use by learning about our first
routing protocol: RIP.
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