how can i know the users connected to my system
 

Hi
My system i connected to the network and i am using it through other system using SSH. I have some other friends accessing the system at same time. How can i know who are connected and their IP addresses? if i want to send a message to a connected system how can i do that??

Also I have a broadband connection and i get the IP adresses through DHCP and it will be in the range 192.168.1.XXX. How can i know my gateway, DNS and IP address that ISP has provided to me.

for the system you are connected to: "who" does it
Dave

"w" also works and gives a little more info

These commands are standard in all distributions:
w
who -a
users
who and users show who are currently logged on. You can also use last:
last
Last looks through /var/log/wtmp and displays a log of the last users logged on, including those currently logged on.
Another possibility is to get the users-information from the systems logs:
grep sshd /var/log/messages

you could try looking at the netstat utility. type 'man netstat'. this program has many options and could be what you need to see all open connections on a particular machine.
just a thought.