Using IP SLA with Route-maps

July 19th, 2009

I recently came across a problem that is not an uncommon problem that small businesses face. I came up with several solutions to their problems and I thought I would take a minute to discuss one of those solutions. This customer has a business requirement to use a proxy server for all outgoing web traffic. This on the face of it seems like a simple problem, there are many good proxy vendors out their such as my favorite vendor Blue Coat. There are many free alternatives such as Squid Caching Proxy server.
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Introduction to Filter list for JUNOS

June 14th, 2009

Junipers JUNOS is a very robust operating system, not only is the OS very advanced but the ASIC heavy design of Juniper hardware is akin to calorie free chocolate bars! Juniper Filter Lists which are non-stateful packet filters similar to Cisco Access-Lists are compiled and processed using hardware, what this means is that you can have as many Filter-Lists as you want and as long as you want without degrading performance.

Juniper is also big on naming things, in JUNOS everything has a name, the Filter Lists have names, the terms in the Filter Lists have names, and even the address’s you are matching on have names. This is a big concept in JUNOS because it allows you to write snippets of Filter-Lists and use them for many different Filter Lists. JUNOS also supports grouping Filter Lists and applying an entire group of filter to an interface. If you apply Filter groups to a JUNOS interface they individual Filter Lists are evaluated in order sequentially.
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New TechCast Posted

June 13th, 2009

I have been busy lately, I am in the middle of a Data Center migration at work, which is eating up hours of my personal time, and I have a million other projects on the burner. I have fresh content coming but in the mean time, I did a TechCast on Junos, please view the video at http://www.exiletv.com.

Until Next time

gopher

February 4th, 2009

I have been continuing to setup the bbs software on bbs.techinvasion.net. I have added irc, gopher, finger, and ident functionality. I encourage all of you to drop by and experience this neat software. The really neat thing about this BBS software is that it connects you to a world of forums and message boards that can only be accessed using BBS software. If you are running firefox I encourage you all to go to gopher://bbs.techinvasion.net. This will let you view the forums and posts, although it doesn’t look the same as it does through a telnet session, it is still very interesting.

Blast From the Past – BBS.Techinvasion.net

February 2nd, 2009

Recently as a project cleaning up some old files and software, I came across a software disk for an old BBS I used to run. This got my interest peaked as I wondered if there were still BBS systems Alive and well on the internet. Information on BBS systems was few and far between in my research and it took me a while to make some headway. Eventually I came across http://Synchro.net  BBS software. This software is very similar to old school dos BBS’s. I installed the software which was no small feet given the inadequate build instructions. Once the system was built and installed I had allot of fun setting up classic door games such as Trade wars and others.

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Rotary Pools for Semi-Static NAT / Port range Forwarding

December 22nd, 2008

 

Cisco routers have a very robust network address translation feature set. The NAT software allows you to control translation with access-list, route-maps, and destination pools. With the wide array of commands, it is sometimes difficult for beginners and experts to figure out how to combine these elements to solve a problem.

 

 

 

 

 

 

 

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Content Based Access Control “CBAC”

October 21st, 2008

In the beginning God created heaven and earth, and then he created routers, so packets could flow from one part of the earth to the other. As he rested he looked down on his creation and smiled for all was good. Packets were flowing from one interface to another. Then as he beheld his creation he watches as some pad packets decided to flow where they didn’t belong! So God created access-lists and again everything was as it should be, packets only flowed to areas where they belonged. After some time naughty packets found out that they could sneak by God’s great protectors of the network by setting the ACK bit in their headers.

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Introduction to access-lists part 2

October 16th, 2008

In the second installment of our guide to access-lists we are going to talk a little about named access-lists, how they work, what the benefits are, and how using them allows us to create reflexive access-lists. Named access-lists are exactly what they sound like, they are an extended access-list that has a name instead of a number. One of the nice features of named access-lists is that each line of the access-list has a number. this way you can delete just one line in an access-list without removing the whole access-list. You can create a named access list by using the following command.

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Introduction to access-lists part 1

October 15th, 2008

Today I would like to take some time and talk about security. I want to discuss access-lists, extended access-lists, reflexive access-lists, and CBAC or content based access control. Learning how to properly use access-lists is so crucial to becoming a good network administrator. They are vital to securing your network and as you progress with your studies you will find that access-lists are used quite extensively in routing, QoS, and other important things.

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Replace a running config without reloading!

October 4th, 2008

The new Cisco IOS 12.4 train has many new features that any engineer will find useful; one of the features that fix a pain point for me is the new config options available in 12.4. Have you ever been in a situation where an entered configuration does not work as expected? Now usually you have to back out the configuration one command at a time and hope for the best. Sometimes you may even reach a point where you can not completely remove a configuration without reloading the device, this is the case sometimes when trying to remove sub interfaces. Now if this is a datacenter or work environment then you may not be able to reload the router.
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