Category Archives: Uncategorized

Aws for network engineer

https://aws.amazon.com/blogs/apn/amazon-vpc-for-on-premises-network-engineers-part-one/

Linux insides

https://github.com/0xAX/linux-insides?files=1

vsrx 15.1 problems

WARNING THIS IS A DIRTY HACK!

After our Openstack upgrade to Kilo I experienced problems when launching a vSRX 15.1.  The image would boot to “Wind River Linux 6.0.0.15” prompt but wouldn’t actually launch the freebsd VM within the nested KVM instance.

The problem is related dmidecode reporting it doesn’t fuly support SMBIOS 2.8

root@localhost:~# dmidecode | head
# dmidecode 2.12
SMBIOS 2.8 present.
# SMBIOS implementations newer than version 2.7 are not
# fully supported by this version of dmideode.
blah blah blah

 

I am guessing various Juniper scripts parse dmidecode output to make sure the VM is the right shape and size before launching the nested KVM VM.

We can solve the issue by creating a wrapper script that will call dmidecode and grep out the warning messages about SMBIOS.

eg.

root@localhost:/# which dmidecode
/usr/sbin/dmidecode
root@localhost:/# mv /usr/sbin/dmidecode /usr/sbin/dmidecode.orig
root@localhost:/# vi /usr/sbin/dmidecode

root@localhost:/# cat /usr/sbin/dmidecode
#!/bin/bash

/usr/sbin/dmidecode.orig $@ | grep -v " SMBIOS implementations newer \| fully supported by this "

root@localhost:/# chmod +x /usr/sbin/dmidecode

You can now Shutdown your instance, take a snapshot of the fixed image and use that to launch new vSRX in the future.

 

Other bits of interest 😉

/usr/sbin/vjunos-console.sh
/usr/sbin/platform_hw_functions

https://marklodato.github.io/visual-git-guide/index-en.html

http://baturin.org/docs/iproute2/

Python Programming for the Humanities: An interactive tutorial

http://fbkarsdorp.github.io/python-course/

Srx ansible

http://jedelman.com/home/juniper-vsrx-automation-with-ansible/

Pi speed tester

http://www.recantha.co.uk/blog/?p=13607

Let’s Build a Web Server, Part 3

http://ruslanspivak.com/lsbaws-part3/

How TCP backlog works in Linux

http://veithen.github.io/2014/01/01/how-tcp-backlog-works-in-linux.html