Skip to main content

CCNA Recap: Port Security



Trunk ports and Etherchannel ports are not eligible for Port Security.
Why?

Etherchannel ports are bundled logically to look like one link with larger capacity than a single link.

Trunk ports carry all traffic.

switchport mode access
switchport port-security



Port security
  • does not care where frames come from (local device or other switches)
  • Watch incoming frames, keeps list of source MACs & counter of source macs

Sticky Secure Mac Addresses
  • Port security learns mac of each port and stores them so you don’t have to put in everyone by hand.
Because it's a switch  - Layer 2 - It's all about MAC Addresses.




show port-security [interface] #

Secure Shutdown
  • interface has been disabled because of port-security detecting a MAC address it doesn't recognize.

Protect
  • discards traffic

Restrict
  • Discards Traffic
  • Sends log / SNMP messages (161/162)

Err-Disabled Shutdown
  • discards traffic
  • Sends log / snmp messages
  • +1 violation counter per frame
  • disables interface and discards all traffic
  • default setting

Sticky

  • When someone plugs into the port, the switch remembers it. If someone else tries to, the port doesn't work.
Further Reading;

Switchport Port Security Explained

EMPLOYERS: This is me putting new skills into practice.
Labels:

Comments

Post a Comment

Popular posts from this blog

Connecting IoT Devices to a Registration Server (Packet Tracer, Cisco)

In Packet Tracer, a demo software made by Cisco Systems. It certainly has changed a lot since 2016. It's almost an Olympic feat to even get started with it now, but it does look snazzy. This is for the new CCNA, that integrates, among other things, IoT and Automation, which I've worked on here before. Instructions here . I don't know if this is an aspect of "Let's make sure people are paying attention and not simply following blindly", or an oversight - The instructions indicate a Meraki Server, when a regular one is the working option here. I have to enable the IoT service on this server. Also, we assign the server an IPv4 address from a DHCP pool instead of giving it a static one. For something that handles our IoT business, perhaps that's safer; Getting a new IPv4 address every week or so is a minimal step against an intruder, but it is a step. There are no devices associated with this new server; In an earlier lab (not shown), I attached them to 'H
Post a Comment
Read more

Securing Terraform and You Part 1 -- rego, Tfsec, and Terrascan

9/20: The open source version of Terraform is now  OpenTofu     Sometimes, I write articles even when things don't work. It's about showing a learning process.  Using IaC means consistency, and one thing you don't want to do is have 5 open S3 buckets on AWS that anyone on the internet can reach.  That's where tools such as Terrascan and Tfsec come in, where we can make our own policies and rules to be checked against our code before we init.  As this was contract work, I can't show you the exact code used, but I can tell you that this blog post by Cesar Rodriguez of Cloud Security Musings was quite helpful, as well as this one by Chris Ayers . The issue is using Rego; I found a cool VS Code Extension; Terrascan Rego Editor , as well as several courses on Styra Academy; Policy Authoring and Policy Essentials . The big issue was figuring out how to tell Terrascan to follow a certain policy; I made it, put it in a directory, and ran the program while in that directory
Post a Comment
Read more

Create a Simple Network (Packet Tracer) + A Walkthrough

Again; I've done this, but now there's so many new things, I'm doing it again. The truly new portions were...everything on the right side of this diagram; The cloud needed a coax connector and a copper Ethernet connector. It's all easy to install, turn off the cloud (Weird), install the modules. Getting the Cable section of Connections was an unusual struggle - The other drop down menu had nothing within. It required going into the Ethernet options and setting the Provider Network to 'cable', which is the next step AFTER the drop-downs. The rest was typical DHCP and DNS setups, mainly on the Cisco server down there. The post is rather short - How about adding a video to it? Find out what A Record means - This site says 'Maps a name to an IP address', which is DNS. So it's another name for DNS? You can change them (presumably in a local context) to associate an IP address to another name.
Post a Comment
Read more