I was configuring a switch the other day and realized I had configured a trunk on the wrong port. God, I hate that. Instead of dumping the configuration for the port and doing a “no” on each line, I used the default command. Switch(config)#default interface G0/1 This resets the configuration on interface G0/1 to how […]
Aaron's Worthless Words
It's possible that someone somewhere needs to know this.
It looks like there was another bad BGP announcement over the weekend. This time, a 24-bit network belonging to the country of Kenya was being advertised by Above.net. The heart of the problem is the same as it was with the YouTube problem a few weeks ago: someone who wasn’t authoritative for a network began […]
NATting sucks and can be confusing. I’m sure everyone agrees to that, but you have to use it at some times. In a PIX/ASA, it’s easy to configure a simple setup, but can be super-complicated in larger networks. In a simple lab, we have set up an ASA with inside and outside interfaces, with the […]
There’s a very-overlooked feature of access-lists — the remark. Yes, this is very basic, but it’s worth mentioning, as it has saved me anguish time and time again. I use remarks to document each line of an ACL (on IOS, PIX, FWSM, ASA, etc.) so that when I go back later, I actually know what […]
We all have these at our desks. Not the bluetooth guys for your [tag]phone[/tag] (we could talk about that for a while), but the 900MHz headsets that your company gave you for those long and annoying calls with the boss. These things rocks, but they are oh-so [tag]insecure[/tag]. A coworker who fields support calls has […]
I’ve been looking around at some lists and forums for technical help on Cisco gear, and one thing keeps coming up — people new to [tag]Cisco[/tag] devices don’t know how to look at logs. The [tag]logs[/tag] are your friends and a great tool. You can use them to see what your router is doing, what’s […]
BGP has issues; the main one being transitive [tag]trust[/tag]. [tag]BGP[/tag] works by having networks (companies, providers, etc.) advertise [tag]routes[/tag] that it owns to its peers. These peers pass those routes on to their peers, ad nauseum, until everyone knows what networks everyone has. The big assumption here is that you are advertising only networks for […]
I deployed a Cisco ASA at a location and couldn’t get logged in via SSH. I would get prompted, but, no matter what username/password I put in, it would just reject me. After some digging, it turns out that I forgot this command. aaa authentication ssh console LOCAL When I put this in, it let […]
Back in the day, when I used to put a new piece of IOS-based gear on the network, I would have to go through the gear already in production to remember what all those “little configurations” were that kept the devices running. Guess how many times I remembered to set the NTP server or turn […]
I got my CCNP certification library the other day to finally get myself another cert, so I’ve been doing some reading of late. The thing I hate about certs is that, even if you have all the experience in the world, there’s always a whole mess of academic stuff that no one really knows or […]