In this configuration I’m at looking at using Microsoft NPS 2012 R2 as radius server and I’m going to skip the installation of NPS because it really is just a next, next, finish installation. In this demo I already have this NPS system connected to a Windows domain, my goal is to create role based access on Cisco IOS routers while using radius to login. I’ll have a couple for active directory accounts each them will represent different types of allowed access to these IOS routers. One account will get full administrative access while the other will only get read access, how cool cat is that 😉 !
Well its 2016 and you still have that one-of-kind Cisco ISR 2811 or 3845 running in the environment? You followed and installed Rancid, all the new stuff works like it should but when you try to connect to that “one-of-kind” 2811 with Rancid it closes the connection…
This is a simple fix and the bug is reported here: LINK. The bug is something with OpenSSH which is installed on your Linux operating system and Rancid rides on top of it. You would have the same issue if you just tried SSH to thing directly from your Rancid machine. The bug looked to be fixed starting OpenSSH 6.9 but as right now at least in Centos 7 the version it goes up to is OpenSSH 6.6. You can verify this by using sshd -V to output the OpenSSH version you are using.
Simple fix is to modify the ssh_config file usually located at /etc/ssh/ssh_config and at the bottom of the file put the host you are connecting to. Copy what you have in your router.db file meaning if you are using DNS names put DNS names of the devices that won’t connect into this file. If you are using IP address use IP address in this file. In this example I’m using IP addresses and DNS names, the following is at the bottom of the ssh_config file:
# Custom Rancid Configuration (Issues with Connecting SSH with Older Devices) # Bug Report 740307 https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=740307 # Host 192.168.3.1 KexAlgorithms=diffie-hellman-group14-sha1 # Host Router03.example.com KexAlgorithms=diffie-hellman-group14-sha1 # Host Router02.example.com KexAlgorithms=diffie-hellman-group14-sha1 #
You should be good to go after that. You can test this by using clogin or by connecting directly. If you noticed on the bug report you could also up the Diffie-Hellman size to 4096 on the router itself by using the ip ssh dh min size 4096 command as well. I hope this helps if you ever need it 🙂
Cisco released VIRL almost a year ago and it’s not at the 1.0 version yet but it’s getting close as they have done some good work towards the product since it first lunched. Cisco VIRL is like GNS3 which is simulation platform that runs Cisco’s current operating systems so instead of buying used Cisco hardware you can run this program on your computer. This software is geared towards proof-of-concept designs, for personal and training on Cisco Certifications. Let’s talk about it!
We have to start somewhere so let’s look at the basics of configuring OSPF. Remember OSPF is an IGP (Interior Gateway Protocol) and allows packet authentication as well as IP multicast when sending and receiving updates. In this post we are configuring OSPF in a single area. Continue reading
So I don’t write much powershell but recently I needed a way to send daily emails out of PRTG. Thanks Paessler which has kept it simple with their PRTG monitoring system as the hardest part of this script was getting the data in HTML. (Remember I don’t write much powershell. 😉 ) If you have not used PRTG before check it out if you need some alerting in your environment. Personally this is one of my favorite systems for just monitoring because a lot of other monitoring systems include everything but the kitchen sink and reality we just need to know what’s up and what’s down. Continue reading