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Routers & Modems Forum => Misc => Topic started by: macnext1 on November 21, 2009, 12:00:27 PM

Title: IP Addresses
Post by: macnext1 on November 21, 2009, 12:00:27 PM
You all know that I have never really understood all this IP address stuff so here is one of those questions that will probably warrant a 'well duh'. My desktop and laptop are hooked in to my TreandNet router. Their addresses are respectively 192.168.10.101 and 192.168.10.102 -- the Trendnet has an IP of 192.168.10.1

There is also an HD DVR hooked in to the Trendnet and of course 2 modems.

Now the question -- if I go into the Trendnet and change it's IP to 192.168.9.1 -- would that work? And what all would I have to change to work with it?

Would the computers just automagically figure out (via a reboot) where they were and like magic become 192.168.9.xxx? What about the HD DVR?

Mac

Title: Re: IP Addresses
Post by: Shane on November 21, 2009, 12:04:43 PM
Thats the great thing about DHCP, it is a automatic way of the computer getting the IP info it needs from the router. So as long as none of the computers or the dvr is using a static ip(one that never changes) then yes they should all grab the new info after a reboot.

Shane
Title: Re: IP Addresses
Post by: Evan on November 21, 2009, 12:47:06 PM
Mac,

Do you need your IP address changed for some reason?  Does the DVR manual tell you do that?  You can try it and if anything doesn't work after you do that...then just go back in a "flip" the switch.  I'm still curious though...do you need to change it or are you just trying to understand this better?  We can give different info depending on "why?".

Good to see you back in the forums, btw.  I hope everything has been well with you.

-Evan
Title: Re: IP Addresses
Post by: macnext1 on November 22, 2009, 12:27:05 PM
I guess it's a little bit of both reasons. There is a site that is tracking me and I would like to figure out if it is a cookie or some other kind of file they have planted on my system or is by the IP address? I've kinda looked for cookies and didn't find one. So I figured if I changed the IP address then that would eliminate one possibility. The other reason is to just MAYBE get a little smarter.

Mac
Title: Re: IP Addresses
Post by: Evan on November 23, 2009, 05:43:29 AM
Did you try changing the address yet to see if it would still work?  If yes, then what was the outcome?

As far as some site tracking you, that is either going to be do to a cookie or malware.  Did you find out about this through a virus scan or some other method?

-Evan
Title: Re: IP Addresses
Post by: macnext1 on November 23, 2009, 06:52:06 AM
I have not tried changing it yet. Are there any gotchas I need to watch out for? For example I have a DVR attached to the router and it requires 2 port addresses be forwarded, I'm assuming that even if I change the router IP that the port addresses that have been forwarded will still work. But what else should I watch out for?

I think all I really need to do is change the address in the router. Reboot both systems. Go back to DirecTv and tell it to check for network connection again. That's it. Bada Bing, Done. Does that sound right or did I leave something out?

Mac
Title: Re: IP Addresses
Post by: Shane on November 23, 2009, 08:51:27 AM
Changing your local IP isn't going to do anything for ya, maybe make a head ache cause you'll have to setup port forwarding again.

Are you looking more towards getting a new Internet IP? there are some simpler tricks for that.

Shane
Title: Re: IP Addresses
Post by: macnext1 on November 23, 2009, 09:21:39 AM
See now you're talking about something I really don't understand. I thought if I changed the router IP then the Internet would see me as a different IP. Not so? Thanks to you setting up the port forwarding is a piece of cake. But if the world (Internet) will see no difference in my IP then I reckon I won 't accomplish anything.

So how do I go about establishing a different IP for the Internet to see?

Mac
Title: Re: IP Addresses
Post by: Shane on November 23, 2009, 09:34:10 AM
See you have 2 sets of IP's.
Your ISP gives you a internet IP through the modem. But this IP is only good for one computer as it is only 1 IP. A router is used to take this IP and then route the internet to multiple computers. Thus the name router :-)

So changing your local IP (from the router) wont do anything your looking for. What we need to do is change the IP on the internet side, which requires very little for you to do.
There is 2 ways to do this, for ISP's like cable they give an IP out then remember the IP by the MAC address of the router or computer. To change it you just need to log into the router and change it MAC address then reboot the cable modem. The modem will see a new MAC and give it a new IP.

DSL is different, and since I don't have DSL I cant test to find the easiest way. But your ISP does change your IP unless you pay for a static IP. So with dsl sometimes leaving the modem unplug for a while and then plugging it back in will get you a new internet IP as well.

Shane
Title: Re: IP Addresses
Post by: Evan on November 23, 2009, 09:58:16 AM
Shane, Mac has Satellite and DSL, so it is going to be a little "trickier" than initially thought.  Wouldn't you think he could call his provider and them to issue him a new IP and tell them he believes someone is watching his current IP.  I would think that would be enough to get them to comply.

Quote from: Shane
To change it you just need to log into the router and change it MAC address then reboot the cable modem. The modem will see a new MAC and give it a new IP.
Don't some ISPs look for the MAC address of the modem itself.  I know with mine if I use a different modem then I have to contact them and give them the new MAC...they don't care about the router though.

Mac, like Shane said, the router takes the Internet IP and basically creates it's own little internet for your home.  The "192.168.10.1" is that new "local" internet that's just for you.  That number can only be seen and used from inside your network, which is why it's okay to post in the forum.  You Internet IP is the same as your home address.  If people know that then they know exactly where you're located.

But like I said before Mac, do you know if you need to change your Internet IP?  You might have a different issue.  Do you just want your Internet IP to be different so that you can't be "seen"?

-Evan
Title: Re: IP Addresses
Post by: Shane on November 23, 2009, 10:15:39 AM
Im talking changing the MAC of the router not the modem :-P

Shane
Title: Re: IP Addresses
Post by: Evan on November 23, 2009, 10:32:36 AM
I know.  But my point is if I changed the MAC of my router (or switched router itself) then it wouldn't have any bearing on my Internet IP, because my Internet Provider is looking at the MAC of my modem (not my router).  I would still be using the same modem so it would retain the IP provided by my ISP. I can check that tonight and I'll recant if I'm incorrect.  :thinking:

-Evan
Title: Re: IP Addresses
Post by: Shane on November 23, 2009, 10:49:13 AM
The IP isn't handed out to the MAC of the modem. The MAC of a cable modem is used to see if that modem is allowed on that cables network. The IP is then given to the computers/routers MAC address. This is also how a cable modem can give out more than 1 ip address when a custom pays for it. Switch routers, reboot the cable modem and you will have a new IP, try it. Ha! score one for Shane! LOL  :artist:

Shane
Title: Re: IP Addresses
Post by: macnext1 on November 23, 2009, 12:51:26 PM
That's ok guys keep going I don't really think I can get any more confused. LOL

So -- Evan, it is really an issue of I don't want to be 'seen' by this particular site.

Folks, I went to a site 'whatsmyip' and so I see what you mean. The Internet address points to my house and then my IP (within my house) gets the information to the right computer -- right? So you wind up with an address like xx.xx.xxx.xxx/xx.xx.xxx.xxx

Now a REALLY simple question -- how do I determine for sure (without unplugging one) which computer has what (within my network) address? I pinged both and of course I get an answer from both. The problem I have (with understanding) is that the site where I don't wish to be seen has my local address different from what I thought it was (in other words either I or the site is messed up). Couldn't possibly be me -- LMFAO.

Mac
Title: Re: IP Addresses
Post by: Evan on November 23, 2009, 01:23:50 PM
Mac, just look at the IP address that listed at top right of Simple Port Forwarding.  Whatever computer you are running the program from will its IP listed there.

You can also bring up a command prompt (Start->Run->"cmd" without quotes) and type "ipconfig" and that will tell you the IP of the computer you run the command from.  :wink:

If you log into your router you should be able to find these same numbers listed there too (along with the other computer and the DVR).

To keep from being confused just read Shane's last comment.  I had 1 tiny party wrong on mine, which I will edit, but we talked about it and his last comment is the clearest.  :smiley:

-Evan
Title: Re: IP Addresses
Post by: macnext1 on November 23, 2009, 01:58:27 PM
Evan -- IPCONFIG did the trick -- apparently I must have screwed something up at some point because it appears that my local addresses have all shifted one position. No biggee.

Now let's go back a bit. Can I just change the MAC in  the router and reboot systems and I will then have a new Internet address? OR is there something else to be done at that point? And what in the world should the MAC be changed to -- right now it has 00-14-d1-61-aa-9d 
I obviously have no clue of what to change or what to change it to.

Mac
Title: Re: IP Addresses
Post by: Evan on November 23, 2009, 02:29:16 PM
If you change the MAC just change the last value (d) to something else (e would be good).  Then for the least amount of hassle you need to:
That is what I would do with my cable internet set up.  But that is because of how Shane explained the Internet IP address and the modem/router set up.  With DSL you set up everything a little different and I'm not 100% on the satellite.

You might want to wait for Shane to provide additional input.  You can try though and just be sure to take note of the old MAC of the router if you need to change it back.

-Evan
Title: Re: IP Addresses
Post by: macnext1 on November 23, 2009, 03:49:22 PM
Ok, I've got all that. I'll wait for Shane. I don't suppose DSL or satellite would be a great different from cable but we'll see what Shane has to say.

I have another clarification point. My Internet address is xx.xx.xxx.xxx/yy.yy.yyy.yyy where the x's were assigned by ??? my ISP? Maybe? The y's are what was generated here in my house by my ??? router? Maybe? And somewhere in this world there may be a lot of houses that have the exact same set of x's but they don't have my y's -- correct?

Oh, another question. IPCONFIG is gonna nail down the other system when I can get on it tomorrow but how can I determine the IP of the DVR? Well durn, never mind -- it's right there in the router (had to go to the bottom of the page) -- duh. LOL. However, while there I see that each host (CPUs and DVR) have a different MAC address. What's up with this anyway. I should know better than to go looking around, it just raises more questions. I know you're gonna point me towards some bending 'stuff' to read, OK. LOL I love you guys (you are almost as patient as my wife).

Mac
Title: Re: IP Addresses
Post by: Evan on November 24, 2009, 06:41:32 AM
Alright, let's see how much I can help you out.  :wink:

Quote from: Mac
My Internet address is xx.xx.xxx.xxx/yy.yy.yyy.yyy where the x's were assigned by ??? my ISP?
Yes, if you are moving down the line from your ISP to your modem.  That is your "unique" Internet Address.  You can also go to http://www.pcwintech.com/port_test.php and that will show your Internet IP.

Quote from: Mac
The y's are what was generated here in my house by my ??? router?
Yep, your router gives you the private IP.  That might be somethign 192.168.1.1 and then the first computer could be 192.168.1.2 then .3 then .4 and so on.  In your case your router is using 10.xxx.xxx.xxx same idea though.

MAC address' are just hardware IDs (like barcodes).  There is a naming scheme involved where the first part is suppose to represent the mfr and last few values get more specific.  If you change the MAC address then the router will think it is a new device, nothing more.  The MAC address doesn't tell the router what a device is (other protocols do that), it's pretty much the same as "take a number" at the D.M.V.  :wink:

-Evan

Does that answer everything for you?  :smiley: 
Title: Re: IP Addresses
Post by: macnext1 on November 24, 2009, 07:36:33 AM
Almost. What about the part of my question relating to x's and y's?

Ah, and another question. In the router is has a button labled 'Clone MAC'. What's it do? Would it provide a new MAC? Do you know if there is an easy way to recover from the change in the MAC if it all goes south (kinda like Windows 'restore to an earlier date'?

Still waiting for Shane to weigh in before I muck with MAC address.

Mac
Title: Re: IP Addresses
Post by: Evan on November 24, 2009, 07:54:45 AM
My bad on the x and y question.  I missed the last sentence
Quote from: Mac
And somewhere in this world there may be a lot of houses that have the exact same set of x's but they don't have my y's -- correct?
Incorrect if the x's represent your Internet IP.  Remember, I'm thinking in terms of working my way down from the internet to your computer.  Internet IP will be unique and you shouldn't let that be seen (the number that is shown at http://www.pcwintech.com/port_test.php) but the local IP will be the same in many households.  For instance, Linksys uses 192.168.1.1 for all of it's household routers.  So if you went over to some one's house and they have a Linksys type "192.168.1.1" into the address bar of a browser and you'll get the router log in page. (IPCONFIG will show this as the "default gateway").

Quote from: Mac
Ah, and another question. In the router is has a button labled 'Clone MAC'. What's it do?
Say your ISP made you set up your internet connection with your computer (before you used a router) and you had to enter the MAC address of the computer (or is was pulled automatically).  The modem would be "tied" to that address.  If you wanted to have more than that one computer on the internet then you'd add a router between the modem and computer and then "Clone" your computers MAC so that the modem/ISP thinks it's the same device.  Presto! Instant network.

As far as recovering from a changed MAC, you just need to go to the same area you changed it in the first place and put the original value back.  This will be different depending on if you are talking about the computer or router.  You probably can't change the MAC of your DVR though.

-Evan
Title: Re: IP Addresses
Post by: macnext1 on November 24, 2009, 02:56:28 PM
Thanks. I think one of us got the x's and y's switched around but bottom line is the first part is unique to me and points to my house. The second part might be duplicated in 1000's of other houses.

I'm gonna send you an Email about another item later.

Thanks for the help on this one --- still waiting for Shane to weigh in before I try anything (coward).

Mac
Title: Re: IP Addresses
Post by: Shane on November 24, 2009, 03:03:49 PM
OK since your not on Cable internet here is all I want you to do.
First go to http://www.pcwintech.com/port_test.php and write down the Internet IP you get.

Now unplug the dsl modem. Leave it unplugged for say 10 min if you can.
Then plug it back in. Wait till you are back online then check http://www.pcwintech.com/port_test.php again and see if the IP has changed.  :wink:

Shane