# Why We Need Three-Way Handshake in TCP

Today I go over the concepts about TCP, and pay special attention to the Three-way handshake, the necessary actions before our hosts start to communicate over TCP.

In this post I am gonna make a clear illustration on why three-way handshake is important, besides we will have a network packet capture experiment with tools, tcpdump and wireshark, to give a vivid demonstration of how three-way handshake works.

# Apache Version and Setting Changed in OS X Yosemite

Today I just upgraded my Mac to 10.10 Yosemite. Before I could even be able to enjoy the new UI style in Yosemite, I found that my personal wiki server was not working any more! My god, get down to work...

My wiki KMS is based on dokuwiki, which depends on Apache and PHP. It seems the new operating system overrides the current setting of Apache, to be exact, changing it from Apache/2.2.24 into Apache/2.4.9.

What problems can this lead to? When you visit your local or remote server as usual, it responds with the following error:

 +------------------------------------------+
|                                          |
+------------------------------------------+
or
+---------------------------------------+
|403 Forbidden                          |
|                                       |
| You don't have permission to access   |
+---------------------------------------+


# Works Applications Written Test 2014

Just submit the code for the test of WAP. There are two problems in the test, not so easy(at least for me :(), but I have learnt quite a lot during the test. Now let me show them here for you.

• Dynamic Programming with State Compression
• Persistent Data Structures

# Vim-spf13 Distribution and MacVim

## Vim-spf13

I have been using Vim for over one year, but I still don’t get the hang of configuring and managing it well.

• At first, I use this stuff - dotfiles, which make the vim files slightly organized.
• After that, I get to know pathogen from my friend, and it saves my life by managing the all vim plugins at one place.
• And by now, I think I finally reach the end.

vim-spf13 is a kind of vim distribution, integrating many popular plugins and setting up neat and well-commented vim scripts for you. Althought it does take some time to learn some of it’s usages, but definitely it will be worth your while.