Updating my Network Structure: Conclusions

In my last post, I discussed how I was going to be updating my network structure.

Everything went pretty well with the update. The biggest hurdle for me was that I forgot that your Pix’s Internal and External NICs can’t be on the same subnet. I decided to just go for it, as that wasn’t really a big deal since I had to change every-thing’s IP anyway. I actually ended up making a third subnet, but more on that later.

The Pix’s IOS was interesting. I’ve done some work on them before, but I’ve never had FULL access, and I’ve always had someone who can follow behind me and show me what to do. This was my first full-on experience. I liked how the system handles, but I do have some major gripes about it’s CLI. I know the ASA’s are a big upgraded, so I’ll keep those to myself for now. Except for debugging: Let me say that debugging sucks on IOS. OK, I’m done. Thanks.

I ended up adding a third subnet for VPN-Clients. I need to do some experimenting for a project at work, and so I decided to try setting up a VPN-Server. I followed a guide that was pretty much a “paint-by-number” for setting up the VPN and it worked out pretty well. I did have some arguments between my router and Pix as to who should serve IP Addresses, but that was quickly squashed.

 

Overall, it was a good experiment. I learned a lot, and I have a better grasp on what I need to learn.

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Updating my Network Structure

I’ve decided it’s time to update my network and re-organize things. I’ve been adding things ad-hoc for a while now, and it’s time to give some structure. I need to re-organize my servers, network equipment, and IP Addresses. I’m going to reorganize on the Physical and Network Layer.

 

I’ve documented how my network currently looks:

 

And then I’ve documented Phase 1 of how I want it to look:

 

Basically, I’m just putting the Pix in front of all my servers, putting a managed switch in place, and adjusting my IP Addressing. And no, I’m not sharing the IPs with you |:P

I do want to keep my Wireless set up on DHCP, so when people come by they can connect without any issues. And I do want to keep one computer on the outside of the Pix for troubleshooting/Internet research.

I do plan on having trouble with the Pix, and trouble with the Switch (as I’m still learning Cisco), but I don’t expect it to be a lot of trouble.

 

Wish me luck!

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Disassembling Binaries

Recently, I had to disassemble an EXE for a side-project I was working on. This was some old software that wasn’t maintained anymore, and wasn’t open-source. I’d never touched assembly in my life. I’m not a great programmer, as you can see by my open-source code (Shameless Plug!). This was quite a task for me. I was supposed to have someone help me with it, but that fell through and I was stuck on my own, in a low-level language that I didn’t know anything about. Great…

 

I disassembled it, and I started messing around. I ended up using Ida, which is a pretty good tool. It has some UI issues, but it’s still pretty friggin cool. I watched some videos online to learn assembly, and they were great. I didn’t really get all of them, but I got the basics of “The Stack”, registers, etc. Then I dove in.

 

If you like debugging, then Reverse Engineering is for you. I started putting debug stops in, and then flipping hex values. Most of it started as guess and check, as I wasn’t sure what switches, if/thens, etc “looked” like in assembly, but with enough experimentation I started to figure it out. While the Internet does have a lot of materials and information on Reverse Engineering, most of it is still just “hacking” and guessing and checking. I don’t think that there is really much of a way around that.

 

Eventually, I figured it out. I got the EXE to do what I want. I’m glad I was able to get it working, and it’s pretty cool to say that I was able to learn it on my own, but I don’t think I’d take on a major project unless I absolutely HAD to. Even if I had a lot of time, it’s not something you want to do unless you don’t mind spending days on one small detail (just to find you were barking up the wrong tree). I was glad for the experience, but I hope in the future I can take on more that I’ve got some help with. I think I would like to learn more of this if I had some guidance, and less pressure, but I did have a great sense of accomplishment by pushing it out.

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