I want to monitor and limit OS X's data transfer while I'm tethering via my iPhone

Question

So, I have an iPhone with Sprint service. They offer a mobile hotspot add-on option. Sprint will offer me 5GB of data transfer under this plan, but then they will charge me extra. Specifically, they will charge me $0.05/megabyte. Now, I'm perfectly aware that five gigabytes is a lot, and I don't think I'll need it... but $50/gigabyte is also a lot of money. I'd like to make extra sure that I don't accidentally use that much.

Because of this, and on general principle, I'd like to have some tools which permit me to do things like:

• Monitor the amount of bandwidth that I've used
  • I think I can do this from Sprint too, but on-the-computer is nice too
  • on-the-computer gives me a possibility of breaking it down by application
• See what sort of programs are using the Internet connection
  • I could use, like, Wireshark, but that's a bit too micro-level to be practical
• Keep those programs, and the operating system, from doing things like "downloading an operating system update" while on the mobile hotspot

In principle, I'm comfortable with hacking things like ipfw from the command line, but have little experience with the particulars of this operating system. Pointers, guides, and the like would be good. An all-in-one suite would also be nice too, and I'd consider paying money for it.

Answer 1

I'll answer each part of your question separately (as you asked it)

Monitor the amount of bandwidth that I've used I think I can do this from Sprint too, but on-the-computer is nice too on-the-computer gives me a possibility of breaking it down by application

Answer: OSSec for OS X. You'll need to do some configuration work. This is a host based IDS that will look at packets in and out of your laptop (you can tell it to monitor just the link between your computer and your iPhone). You will need to do some scripting, but there are forums to help answer questions. This is open source, so there is no cost for the software.

See what sort of programs are using the Internet connection I could use, like, Wireshark, but that's a bit too micro-level to be practical

Answer: The software above can do this, or you can use little snitch. I've used is and have never had a problem with is missing traffic. You can set it to ask every time a program attempts to do something, just the first time, or block all traffic at this time.

Keep those programs, and the operating system, from doing things like "downloading an operating system update" while on the mobile hotspot.

Answer: You are going to have to make sure that automatic downloads aren't turned on. little snitch or OSSec can help with this too. Basically, free is OSSec, and pay is little snitch.