Archive for October, 2012

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 8.4.2.6]. (more…)

Twitt

Trunking and DHCP Across Dell Force10 Switches

Tuesday, October 16th, 2012

I did this lab some time back and thought it would be useful to post. In this lab I use a Dell Force10 S25P (FTOS 8.4.2.6) switch and Dell Force10 S50N (FTOS 8.4.2.6) switch to demonstrate trunking and Dynamic Host Configuration Protocol (DHCP) for multiple subnets. Both of these switches are layer 2/3 switches, however, I use the S25P to do all the routing and use the S50N strictly as a layer 2 switch. (more…)

Twitt

Gratuitous ARP and Basics of Connecting a Cisco IOS Switch with a Cisco CatOS Switch

Monday, October 15th, 2012

Cisco Catalyst C4003

Cisco Catalyst C4003

Some of you may have an old Cisco Catalyst switch laying around that you may want to put to use. CatOS is the old Cisco operating system for Catalyst switches that predates IOS; it can still be found on some of the old Catalyst switches which are now End of Life (EOL). In this lab I connect a Cisco Catalyst 3548-XL (Model WS-C3548-XL-EN) [IOS 12.0(5)WC13] with a Cisco Catalyst 4003 chassis (Model WS-C4003) [CatOS 5.5(20)] to demonstrate basic configuration and switching between the two. Gratuitous ARP is also discussed and demonstrated in this lab. The setup is as shown in the below lab diagram. (more…)

Twitt