I was trying to capture some packets using Wireshark. I could find a lots of ip in the source address tab. Which ip do they represent. Which all packets are visible to wireshark when I run it in my system?
The source-address tab represents the address the packet claims it is coming from. Be adviced that this can be easily spoofed so it may in fact not be the actual sender of the packet.
In your case it may not be trivial to know who all the IP addresses are. However if they are not RFC1918 (private IP addresses) you can run them through a geoip service to learn more about the addresses coming to you.
If they are in fact RFC1918 addresses I would take a closer look at your network to find out who the machines are. In some cases a reverse DNS lookup may help you in identifying the machines.
Geoip using netcat:
Build your file and do the following command:
You can read more about the service here: http://www.team-cymru.org/Services/ip-to-asn.html
Reverse DNS lookup with nslookup:
Wireshark captures all traffic from and to your computer on the interface it is listening on (if it has been set up correctly). So if you for example request a website, your computer will send a request to the server, which then replies with the content of the requested page. These replies will usually have the IP of the webserver as the source IP.