Announcement

Collapse
No announcement yet.

How to resolve external ip address

Collapse
X
  • Filter
  • Time
  • Show
Clear All
new posts

  • How to resolve external ip address

    Hello all,

    I am new here, this is my first post...

    I was wondering how I could resolve my external ip address? My router tells me what it is once I log on to it and I know there are lots of sites that will tell you what your external address is but I would like to know how I can do that myself.

    A friend of mine was having trouble with his router (for private home use). He had no connection after messing with the settings. I asked him for his external ip address so that I could take a look. He didn't know what it was and couldn't look it up, that's what brought me to this forum. Although this info. wouldn't have helped him, since he had no connection, I would like to know just to satisfy my curiosity. Can anyone help me out?

    Thanks,
    phil

  • #2
    Re: How to resolve external ip address

    http://www.whatismyipaddress.com should give you the external address, as it is seen.

    Sorin Solomon

    »»»»»
    In order to succeed, your desire for success should be greater than your fear of failure.
    -
    «««««

    Comment


    • #3
      Re: How to resolve external ip address

      Originally posted by phil_lierup View Post
      My router tells me what it is once I log on to it and I know there are lots of sites that will tell you what your external address is but I would like to know how I can do that myself.
      I may be reading too much into this so apologies if that is the case but just to confirm, unless you get given the same IP address by DHCP every time then you cannot really find out what it is going to be until you are connected. Then sites like Sorinso's suggestion work.
      cheers
      Andy

      Please read this before you post:


      Quis custodiet ipsos custodes?

      Comment


      • #4
        Re: How to resolve external ip address

        Thanks for the reactions.

        As sorinso says, I believe this is the easiest way to do it but I'm still curious as to how it works. You are right, AndyJG247 when you say that my ip may change because of DHCP but the external ip adres of a router won't change and this is what I'm after.

        I have been trying with commands like route print and tracert and pathping to try and get my external ip adres to show up but it hasn't helped.

        I already know what my external ip adres is but there must be a way that I can connect to the router and use something like ipconfig that will give me a readout of the different interfaces. Maybe telnet. Maybe a sniffer could give me the info. I'm looking for. I just want to know how it works.

        Maybe it's only possible from and external address, I don't know. I suppose this question amounts to (almost) usless trivia and I definitely don't want to waist anyones time; however, I would appreciate it if anyone has an idea...

        Comment


        • #5
          Re: How to resolve external ip address

          Your router is either setup with an IP address or it gets one from the ISP. If it actually has one in the config then it will depend on the router. Cisco for example could be something like "show ip interface brief" for example; lots of routers also have management web pages you can use to see the config however some ISPs restrict the management to their own internal support. Did you buy the router yourself or was it supplied?
          cheers
          Andy

          Please read this before you post:


          Quis custodiet ipsos custodes?

          Comment


          • #6
            Re: How to resolve external ip address

            I think that the issue is far more complicated than going to the outside port of the router and see what's in there... You may encounter ISPs that use NAT for their own internal network, or any other type of translation for giving their clients some privacy.
            The only way to be certain about how the Net is seeing you is to make a request to it. Like an HTTP request, sending a mail or logging in to an FTP server. All these are requests that are logged into their specific servers. That is your true address, as any host on the Internet will see you.

            Sorin Solomon

            »»»»»
            In order to succeed, your desire for success should be greater than your fear of failure.
            -
            «««««

            Comment


            • #7
              Re: How to resolve external ip address

              As sorinso says, I believe this is the easiest way to do it but I'm still curious as to how it works. You are right, AndyJG247 when you say that my ip may change because of DHCP but the external ip adres of a router won't change and this is what I'm after.
              Ah, but your external IP address will change because, unless you pay your ISP for a static IP address, your router is getting an external IP address via DHCP which is selecting from a pool of publicly routable IP addresses that the ISP owns.


              I have been trying with commands like route print and tracert and pathping to try and get my external ip adres to show up but it hasn't helped.
              Nice tries, but those are only good for the device that your running them from. So you could plug your computer straight into your modem (bypassing the router) and then do "ipconfig /release" and "ipconfig /renew". Then you'd be able to see your publically routable IP by looking at ipconfig /all.

              You could also look through the management pages of your router for the WAN address. If it has UPnP turned on, you can poke the router with a tool like "Universal Plug-and-Play Tester" and get the external IP.


              there must be a way that I can connect to the router and use something like ipconfig that will give me a readout of the different interfaces
              Depends on the router. Is it a big ol' Cisco / Juniper business class thing or is it a cheap-o netgear? If its a cheap-o home router, it should be somewhere in the management pages.


              Maybe telnet.
              Not quite. However, I've heard that you could telnet to an email server and send it a helo message and it would in turn send you back info about your connection which usually includes your IP address and domain. I've never tried that myself though.


              Maybe a sniffer could give me the info.
              Maybe if you have the ability to port mirror the WAN port, but that seems unlikely if it's a home router.




              Do any of those possibilities help you?



              EDIT: As sorinso points out, if your ISP uses some kind of NAT for their IP space, then your toast and must rely on some kind of external web site to see what you look like to the outside world.
              Last edited by Nonapeptide; 2nd June 2008, 20:08.
              Wesley David
              LinkedIn | Careers 2.0
              -------------------------------
              Microsoft Certifications: MCSE 2003 | MCSA:Messaging 2003 | MCITP:EA, SA, EST | MCTS: a'plenty | MCDST
              Vendor Neutral Certifications: CWNA
              Blog: www.TheNubbyAdmin.com || Twitter: @Nonapeptide || GTalk, Reader and Google+: [email protected] || Skype: Wesley.Nonapeptide
              Goofy kitten avatar photo from Troy Snow: flickr.com/photos/troysnow/

              Comment


              • #8
                Re: How to resolve external ip address

                phil_lierup, I can tell you that both you posts in this thread have used the same IP. If you power cycle your modem then post back here after that, I can see if your IP has changed. Power cycling will usually release your IP and assign a new one, especially if you leave the modem off for 10 or so minutes.

                Incase you are concerned, your IP shall not be posted in the Forums.

                Just checked and you appear to have a Dynamic assigned IP. What is the make/model of your ADSL modem? I also hope you have changed the default password on this device. Please to see the external management interface has not been enabled. If it is not needed, also disable ECHO (called WAN Request on some devices) on the modem.
                Last edited by biggles77; 3rd June 2008, 14:37.
                1 1 was a racehorse.
                2 2 was 1 2.
                1 1 1 1 race 1 day,
                2 2 1 1 2

                Comment


                • #9
                  Re: How to resolve external ip address

                  Veeeerrrrryyyyyy interesting!

                  biggles77, I have power cycled my router. After 10 minutes I powered up again (sheesh that took long!). I have a Davolink DV-201AMR router and the standard password has been changed. Thanks for not posting my IP.

                  Originally posted by AndyJG247 View Post
                  Did you buy the router yourself or was it supplied?
                  The router was supplied and I cannot change much in the settings so I'm assuming it's an unmanaged router.

                  I'm a bit surprised to learn that my external (WAN side) ip can change. I’ve been using this provider for about a year and I know that it’s never changed… BTW, after the power cycle my ip is still the same. I can see this from the mgmt console. I guess I’m lucky because I’m not paying for it as far as I know.

                  Originally posted by Nonapeptide View Post
                  Nice tries, but those are only good for the device that your running them from. So you could plug your computer straight into your modem (bypassing the router) and then do "ipconfig /release" and "ipconfig /renew". Then you'd be able to see your publically routable IP by looking at ipconfig /all.
                  I'm only using my Davolink. It is my modem/router. There isn't any other piece of hardware between my pc and the outside world. I'm directly connected to it. I suppose it falls under the cheap-o category but I am happy with it.

                  Originally posted by Nonapeptide View Post
                  You could also look through the management pages of your router for the WAN address. If it has UPnP turned on, you can poke the router with a tool like "Universal Plug-and-Play Tester" and get the external IP.
                  Thanks for the tip, I'll try it.


                  Originally posted by Nonapeptide View Post
                  Do any of those possibilities help you?
                  Very informative, thanks!

                  Thanks everyone for your thoughts!

                  Comment


                  • #10
                    Re: How to resolve external ip address

                    I'm a bit surprised to learn that my external (WAN side) ip can change. I’ve been using this provider for about a year and I know that it’s never changed… BTW, after the power cycle my ip is still the same. I can see this from the mgmt console. I guess I’m lucky because I’m not paying for it as far as I know.
                    That's not uncommon for a WAN IP address that is technically not static to stay with you for a while. I think I've only had my IP changed once or twice in the last few years. However, some ISPs can change the IP quite frequently. I don't think that happens as often these days. Anyone else care to weigh in on the topic?


                    I'm only using my Davolink. It is my modem/router. There isn't any other piece of hardware between my pc and the outside world. I'm directly connected to it. I suppose it falls under the cheap-o category but I am happy with it.
                    Okay, so with the modem / router combo I don't think that you have the option to directly expose a PC to the WAN. That's generally a good thing. Take a look through the web based management pages and you should find the WAN address in there somewhere.

                    Hope that helps.
                    Wesley David
                    LinkedIn | Careers 2.0
                    -------------------------------
                    Microsoft Certifications: MCSE 2003 | MCSA:Messaging 2003 | MCITP:EA, SA, EST | MCTS: a'plenty | MCDST
                    Vendor Neutral Certifications: CWNA
                    Blog: www.TheNubbyAdmin.com || Twitter: @Nonapeptide || GTalk, Reader and Google+: [email protected] || Skype: Wesley.Nonapeptide
                    Goofy kitten avatar photo from Troy Snow: flickr.com/photos/troysnow/

                    Comment

                    Working...
                    X