Cli on Aaron's Worthless Words

ISCW Notes - Role-based Views

Thu, 05 Nov 2009 00:00:00 +0000

I’m at training for the ISCW test this week, and this topic came up yesterday. Since it came up last week at the office, I figure it was a sign from $deity that it was time for a blog entry.

An admin in another business unit was trying to set up command access for some of his techs. He was going through a couple of routers and assigning commands to privilege levels so that his techs could access them. He was having a boat load of problems, though, and couldn’t get it to work

Using SSH to Run Commands on a Router or Switch

Thu, 30 Apr 2009 00:00:00 +0000

SSH is more than just a shell. You can copy files from and to a server or piece of network gear with it. You can use it to tunnel traffic. Possibly my favorite, though, is to use SSH to run a command on a remote box without interacting with a shell.

One of my biggest pet peeves with IOS (or pretty much any Cisco OS) is the lack of complex filtering. Let’s say I want to look at all the downed ports and interfaces on modules 3 and 6 of my 6509. I can’t easily do that with command from the IOS, but, on my Linux box, I can use multiple grep commands to get exactly what I want really easily. Let’s work through the example, shall we?

Using the Pipe in IOS

Mon, 14 Apr 2008 00:00:00 +0000

A lot of IOS commands give you a lot of information. Most of the time, though, it’s way too much information, and it sure would be nice to do some grep-like stuff on the output, right? Well, just like on Linux, you can use the pipe (|) to do such. That’s not a butt cheek, by the way.

The most useful function is the include directive. This is the equivalent of just plain grep on Linux, and will show you only lines that match a string that you give it. Say that you want to find what ports on your switch are down, but don’t want to grind through all the lines of a show ip interface brief. If you just pipe it to the include command followed by the word “down”, you’ll see something like this.

Common Cisco IOS Commands

Fri, 17 Aug 2007 00:00:00 +0000

Here’s a list of IOS commands that I use all the time that aren’t a part of the basics. I obviously use more than just these, and you do, too, but I hope there’s at least one eye-opener in there.

show env all: Shows the environment status, including fan, power supplies, etc. Good for making sure the environment is alright. show history: Shows your command history since you logged onto the device. Good for remembering what command you put into get those stats the boss needs. Configuration changes don’t show up here. show inventory: Shows a nice list of what the device has hardware-wise. It’s good for a router with a bunch of modules or a switch with a bunch of cards. show interface trunk: Shows all the trunks on a switch along with pruning information. Good for making sure all VLANs are propagating around the network. show interface capabilities: Shows what the interface is capable of doing – not just what’s its configured to do. show interface counters: Shows byte and packet information for every interface. Good for quickly showing statistics without having to look at all the show interface garbage. show mac-address-table: Shows the CAM table on a switch. Good for tracking down where a host is plugged into. show tcp brief: Shows all TCP connections associated with the device like SSH sessions or BGP. show users: Shows who’s logged onto the device. Good for finding a line to clear to kick everyone off the box.