Understanding my ipconfig data.

[Sebouh]

Hi all. I'd like to know what my ipconfig is printing out.

I have a NIC which i use to connect to the internet using pppoe. My ipconfig prints out 2 blocks of data, "Ethernet adapter Local Area Connection" and "PPP adapter spider4". Each has its own ip and MAC address.

I'd like to know why there is a difference in the addresses. Isn't my LAN address the one i use to connect to my network? Yet, when i do an ip scan, i have to search with my ppp id address to get the number of users connected to the network. And why are there two MAC addresses. Isn't there only a single hardware for... which is the NIC?

Thanks for helping.

[sicarie]

Well, why don't you post it (and change the IPs/MACs if you feel more comfortable doing so - it's probably a good idea), and we can go through it with you?

[Sebouh]

Here you go:

Ethernet adapter Local Area Connection:

        Connection-specific DNS Suffix  . :
        Description . . . . . . . . . . . : Intel(R) PRO/100 VE Network Connection
        Physical Address. . . . . . . . . : 00-20-78-16-DF-9C
        Dhcp Enabled. . . . . . . . . . . : No
        IP Address. . . . . . . . . . . . : 192.5.26.96
        Subnet Mask . . . . . . . . . . . : 255.255.255.0
        Default Gateway . . . . . . . . . :

PPP adapter spider4:

        Connection-specific DNS Suffix  . :
        Description . . . . . . . . . . . : WAN (PPP/SLIP) Interface
        Physical Address. . . . . . . . . : 00-53-45-00-00-00
        Dhcp Enabled. . . . . . . . . . . : No
        IP Address. . . . . . . . . . . . : 172.23.6.114
        Subnet Mask . . . . . . . . . . . : 255.255.255.255
        Default Gateway . . . . . . . . . : 172.23.6.114
        DNS Servers . . . . . . . . . . . : 172.23.6.1
        NetBIOS over Tcpip. . . . . . . . : Disabled

Another thing. Can anyone use my MAC address to send me anything, even if i'm connected through an ethernet network? If so, which one from the above (not that they are actually mine...)?

Thanks.

[sicarie]

As I understand it, your PPP connection is the connection you have to your ISP. If you were on a DHCP LAN, you would send out an IP request to 255.255.255.255 , and the local DHCP server would then send out the response with an IP assignment.

However with PPP, you establish a direct link with a device, and then that is set as the gateway for your information.

Sorry about the delay in responding, I was in meetings a lot this week and then had to research PPP - I've never used it (and as such that information may not be 100% accurate, but you can always find out more here ).

I know that in the "hub" era you could certainly send messages using the MAC address, I'm not sure how common or possible that is with switches.

[Sebouh]

Hmmm...i'm still confused though. Isn't the connection with my ISP the first one (Ethernet LAN)? And to access the internet, i have to set up another connection right, a PPP one? So my question is, why? Can't i use the first connection? As i understand it, ethernet also uses a PPP. And is this PPP adapter a separate hardware device, with its own MAC address? And how come my ISP allows me to connect to the LAN with any ethernet MAC address, but only allows me to access the internet (or create the second connection) if i have the permitted MAC address?

Sorry about all the questions. I just wanna now, you know? I'd be greatful if you point me to a website maybe, which explains all these stuff, in case you can't explain or whatever. See i've been taking this networking course this semester, and i've learned so much that, i wanna see how this stuff i learned is being used...

Thanks again.

[sicarie]

Hmmm...i'm still confused though. Isn't the connection with my ISP the first one (Ethernet LAN)? And to access the internet, i have to set up another connection right, a PPP one? So my question is, why? Can't i use the first connection? As i understand it, ethernet also uses a PPP. And is this PPP adapter a separate hardware device, with its own MAC address? And how come my ISP allows me to connect to the LAN with any ethernet MAC address, but only allows me to access the internet (or create the second connection) if i have the permitted MAC address?

Sorry about all the questions. I just wanna now, you know? I'd be greatful if you point me to a website maybe, which explains all these stuff, in case you can't explain or whatever. See i've been taking this networking course this semester, and i've learned so much that, i wanna see how this stuff i learned is being used...

Thanks again.

I *believe* (and I'm sure there are people here who can jump on and correct me if I'm not right) that the PPP connection is coming out of your Ethernet interface, however you have told your computer to go to a specific destination and use that as its internet gateway, so your ethernet information is going over this virtual PPP adapter.

[Sebouh]

Well, after some more research, i found some answers. I understood that ethernet has some limitations, which make it unusable for internet connection. I have to use the PPP protocol which supports authentication. .. So what happens is that the PPP packet is encapsulated inside the ethernet frame and sent to my ISP. So i need to create a PPP connection/session over ethernet, to be able to send/receive PPP packets.

Though i'm still not sure why i have a different ip and MAC addresses. Why can't the ISP just send the packets through ethernet to my LAN address?