RIP timers and reality, #1 (INVALID and FLUSH)

Short article about what really happens with RIP timers. I’ve run some tests putting in situation network advertisements for downlinks and how and when timers react.

The different tests are given in the form of timelines, with the action and reaction at the minute planned. Between brackets you’ll find what should have happened if one of the previous actions was not triggered.

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Linux chage command and timers

The chage command in Linux is used to change the user password expiry information. Indeed, as the administrator, you can control at what frequency users have to change their password. It’s mainly dealing with timers and dates then.

The role of the different chage timers might not be clear for everyone though.

I found it simple to explain them with a timeline, centered around the life of the user password. Around this central timeline, you will find the actions required by the user and the administrator.

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Cisco IP unnumbered inside

What is IP unnumbered?

In Cisco routers, the ip unnumbered <other_interface> command allows you to borrow the IP address of another interface.

Although the Cisco help page explains in detail how to do it, and to some extent the reasons to do so, let’s go deeper and explain the real howto.

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File Descriptor : a simple explanation

What is a File Descriptor? Really, how does it work?

When you don’t have a clear and global comprehension of the Linux system, it’s hard to answer this question. Worse, when you search about File Descriptor on the net, the absolutely only things you’ll find will be either pages about redirections (as if the idea of File Descriptor could be reduced to standard input, output and error) or complicated stuff in C (you can feel my frustration here).

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Copy of VM : interfaces not appearing in Ubuntu

Coucou everyone!

In VMWare ESX (3.0 to 4.1i), you sometimes want to make a copy of an existing VM in production, for example to use the new one as a lab to developp new apps.

There are many ways to do that. The dirty one is simply to copy the VMDK+VMX files of the original VM to a new directory, then adding the VM to the ESX Inventory.

But you have to do it in the proper way for the Ethernet interface to be handled well.

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Just a new article on how to display the author…

…on the WordPress twenty eleven theme.

Just quoting this :

There must be two authors who have both published at least one post. While logged out of WordPress.com create another username account with a different email address. Then add the new username as an Author. Then log-in as the new author and publish one post and backdate it to the date you started the blog. Log-out and clear your browser cache and cookies.

Log in under the original username and you will have an author byline and an author profile below each post. The data for the author profile is from this page > Users > My Profile « About me »