Posts Tagged ‘access lists’

Blocking Hackers From Accessing Your Switch via Telnet/SSH

Sunday, October 21st, 2012

It’s amazing how much rattling at the doors and attempted intrusions companies become accustomed to seeing on their networks. Here I show a simple way to block telnet/SSH access to your switch. First, you should never use telnet to manage your switch over the Internet because the traffic is sent unencrypted and it is therefore insecure; SSH is the better option. Perhaps you only want to manage the switch from an internal network or only want to allow or block some hosts from using telnet/ssh. Below, I block all telnet/ssh access to the switch. I’m using a Dell Force10 S50N switch [FTOS]. (more…)


Cisco – Filtering Unwanted Packets with Standard Access Lists

Saturday, January 7th, 2012

Access lists (ACLs) are basically statements that packets are compared against for the purpose of taking some action if a match occurs. After an access list is created, it can be applied to inbound or outbound traffic; in some cases it is applied in both directions. You can think of an ACL as a method for filtering packets that meet a specific criteria so further action can be taken on them. (more…)