What kind of software do you use to draw diagram for your presentation and report?
Suppose you want to draw a diagram to illustrate the TCP hand shake.
I use visio, but the outcome is too plain.
Is there any free software out there can draw diagrams better? Which can also have some 3D shapes or shadows?
It's PowerPoint 2007, but you have to using basic shapes (with 3D and shadow) to create diagrams. It's possible, but it's hard work, if you want nice looking.
And same nice background for slides. Different for section head and for other slides.
Inkscape is a free vector drawing program that will make drawings as elaborate as you want them to be. And while it's probably not what you're looking for, I can't recommend TiKZ (www.texample.net) highly enough. It's what I use for everything nowadays.
I think you should save yourself a lot of time and look for images on the web, rather than drawing them yourself. Try searching http://images.google.com for what you need (shapes or whatever) and piece them together with a simple paint program or The GIMP.
If you are not publishing the document, and only attempting to explain information to coworkers, you can find (steal) plenty of well-designed images intended to explain networking concepts.
Otherwise your presentation should probably be in PowerPoint or OpenOffice Impress, or some such presentation tool.
If you want beautiful diagrams, be prepared to work for them. Recently, I've been using Illustrator, but that isn't exactly free. I have used Inkscape in the past and it can work very well.
I've filched the company tablet PC for this single reason - so that I can hand-draw diagrams directly in my (OneNote) documents. All the advantages of quick sketches which can be rapidly changed/printed and still have typed text (written text is not a legible option in my case)
Good old Microsoft Paint. Or, Paintbrush on my Mac.
Keeping it simple works for me. As many colors and shapes as I want, with easy canvas features, and nothing over the top like shadows etc.
A whiteboard and a digital camera (maybe in your phone) works really great!
I've found the best of the "free" apps to be Paint.NET. Does everything I've ever need an image creation and editing app to do, well supported by the developers and the community and has a huge userbase that has created a bunch of plugins to expand it's features. As a Photoshop/Illustrator lite, it's as good as they come.