[X4U] How to monitor inbound/outbound network traffic?

[Gretchen Hayman]

On May 20, 2005, at 09:16, Rad Craig wrote:

> Right now, I'm watching the light (xfer) on my network card and  
> it's lit up almost solid, like I was downloading/uploading  
> something, something (data) is going in or out.  I want to know  
> what it is?  Which application is sending it and what its sending.   
> I don't have anything running right now that should be constantly  
> transferring data like this.  Its as if someone is sucking data off  
> of my computer.  Is there a program/app/utility/script that will  
> allow me to find out what is going on?

You can pop open the Network Utility (/Applications/Utilities/Network  
Utility) and use the Netstat portion (or just use the netstat command  
in Terminal).  That will tell you what computers you are currently  
connected to and what ports they are connected to.  Once you find the  
port, you can look it up (in /etc/services or at a ports database on- 
line) and see what application/protocol is being used.

To really see some of the traffic, I'd use tcpdump.  However, it's  
not terribly "user-friendly" if you are used to GUI-based apps.

Do you have your OS X firewall turned on, to prevent unwanted traffic?

--
gretchen