Need a Same IP Address for Internet? How to, Advantages, Disadvantages - Explained

Friends,
Well, as a Web Developer I had to make sure that my servers (which are running in my home PC) are accessible outside of the system. For that, I usually give out my IP Address (Something like 122.XXX.XXX.XXX) to my friends and since forwarding Port 80 is insecure, I would do it at 8088 (PraveenTech Apache Server runs there [​IMG]). This way, it would be helpful to me, as I don't need to change the IP Address of my domain to point it to my home system, each time I connect and disconnect.

Lets see the advantages and disadvantages of it. Later we will see how to implement it.

Advantages
1. Your system will be having the same unique IP Address (122.XXX.XXX.XXX), so that accessing it from other places and bookmarking it will be easier.
2. If you are hosting something, you can remotely connect to your system and start it or stop it.
3. If you own a domain, you can point it to your home server or redirect it.

Disadvantages
1. Your IP Address doesn't change, so you have to adjust with the waiting times when you are a free downloader from File Sharing sites like Rapidshare, MegaUpload.
2. Since you have a permanent identity and some ports are open, your system is surely insecure! Make sure you have a good firewall!

Implementation: How to Set Up DHCP Reservations So You Never Have to Check a Local IP Address Again

[​IMG]

Checking your computer's IP address every time you need it can get tedious. Here's how to set up DHCP reservations on your router so that each computer in your house has the same IP address all the time.

Whether you're using BitTorrent's web UI, forwarding ports for gaming, or streaming media to your phone, you sometimes need to know the IP addresses of your computers. The problem is, if you use DHCP (as most people do), those computers get re-assigned IP addresses every time you reboot them—which means you have to check what it is every time. You can avoid this hassle, however, with something called DHCP Reservations, which let you reserve specific IPs for each computer on your network. That way, they'll always have the same IP address and you never need to worry about checking it again.

Note: If you've heard of static IP addresses before, this is very similar. Since you manage it all from the router, though, it's a bit easier to set up. If, for some reason, you can't use DHCP reservations, you can set up a static IP on each of your computers instead, but this is our preferred method.

Many routers support DHCP reservations out of the box, but if they don't, you can always install the DD-WRT firmware, which adds the support to many more routers. Every router is a bit different, but in general, here's how to set it up:

  1. Head to your router's configuration tool by typing in your router's IP address in your browser's navigation bar. Usually this is something like 192.168.0.1. You can check it by running ipconfig in a Command Prompt, or heading to System Preferences > Network on a Mac.
  2. Find the DHCP reservation setting. This could also be called "DHCP Static Lease" or something similar. On my router, it was under the "Gateway" category.
  3. Head to the computer for which you want to reserve an IP address and find its MAC address. Once again, you can find this by typing ipconfig into a Windows Command Prompt, or by going to System Preferences > Network on a Mac, clicking on your Wi-Fi card or Ethernet port, hitting Advanced, and going to the Ethernet tab. Your MAC address will be in the form 00:00:00:00:00:00. Note that a Wi-Fi card and Ethernet port will have two different MAC addresses, and you can't assign them both to the same IP, so pick the one you use primarily.
  4. Type that computer's MAC address into the first entry in the DHCP Reservation setting. Then, type in the IP address that you want to reserve for that machine. Hit Apply, or whatever button is available to you.
  5. Repeat with any other computers that you want to reserve.

[​IMG]

You should now have a good list of computers with reserved IP addresses, like mine shown to the left. Note that you might have to renew your DHCP licenses on your computers for them to actually start using those IP addresses.

You can do this by running ipconfig /release and then ipconfig /renew in a Windows Command Prompt, or by going to System Preferences » Network on a Mac, turning your Ethernet or Wi-Fi card off, and then back on again. If you then check your IP address (either with ipconfig on Windows or by checking the Network Preference Pane on your Mac), you should see that they have their new reserved IPs, which they'll use every time you turn them on.

Note that this only changes the local IP addresses, so it only works when you're trying to access something on your network. If you're accessing it over the internet, like a Subsonic server, you'll still need to check the global IP address of that machine.

Replies

  • durga ch
    durga ch
    Re: Need a Same IP Address for Internet? How to, Advantages, Disadvantages - Explaine

    I did not understand few things in the above post. Please clarify.
    I above post begins with a global address and ends on a note of private address.
    How is fixing a specific private IP helping someone from outside your network to secure a connection???
    I think there might be an extension to this post of yours which is called NAT (network Address Translation).
    When say X from outisde network i accessing 122.x.x.x , he intends to access your computer.
    In every gateway router there is something called a NAT pool configured. For example
    your ISP might have assigned you a public IP 122.x.x.x and you have 3 computers in your LAN . These 3 computers can look as if they are originatig from 122.x.x.x ,
    becasue you are talking about a server here, the NATing which occurs need to be static NAting, where you for ever map a specific global address to your private address.
    say 122.x.x.x <--> 192.1.1.10
    and thus the DHCP reservation, helps in reserving this specific private address 192.1.1.10 to your MAC.
  • PraveenKumar Purushothaman
    PraveenKumar Purushothaman
    Re: Need a Same IP Address for Internet? How to, Advantages, Disadvantages - Explaine

    How is fixing a specific private IP helping someone from outside your network to secure a connection?
    The IP Address (122.XXX.XXX.XXX) is not a Private IP Address, it is Public IP address of your computer as seen from the Internet.

    How is fixing a specific private IP helping someone from outside your network to secure a connection?
    What do you mean by secure connection here?

    NAT
    My Computer (192.168.1.2) » Router (192.168.1.1) » NAT Takes Place (122.XXX.XXX.XXX) (Public IP Address)

    Your ISP might have assigned you a public IP 122.x.x.x and you have 3 computers in your LAN . These 3 computers...
    Each computer is connected to the Router, in Dialer Mode (PPPoE) and in this mode, each computer would have a different unique IP Address. And I am not denying that, they also have two IP Addresses, one public (122.XXX.XXX.XXX) and another private (192.168.1.X).

    I am unable to explain the last step. I need to check it out practically and will explain it soon. 😀
  • durga ch
    durga ch
    Re: Need a Same IP Address for Internet? How to, Advantages, Disadvantages - Explaine

    your fixing up 192.1.1.0 which is private. DHCP reservation is i think within LAN, you cannot fix a global address 122.x.x.x through DHCP.

    to co-relate 122.x.x.x(global) to your fixed private IP 192.1.1.0 you need to be using static NAT.

    All i am trying to say is - DHCP reservation alone wont help your frinds to access your server, you would be needing static NATing as well to fix that speciifc Mapping between the 122.x.x.x and 192.x.x.x mapping.

    PS: teh screenshot clearly shows its a private IP ( 192.168.0.10)
  • PraveenKumar Purushothaman
    PraveenKumar Purushothaman
    Re: Need a Same IP Address for Internet? How to, Advantages, Disadvantages - Explaine

    Yup the one in the screenshot is a Private IP... Its just an illustration... Well, another method is, you can try fixing the Public IP Addresses here and forcing the connection to connect to this only! 😀 Yeah, I tried it and I have got a 50% success in it... 😀

    [​IMG]
  • durga ch
    durga ch
    Re: Need a Same IP Address for Internet? How to, Advantages, Disadvantages - Explaine

    yes, is is again right.( But this is static Ip configuration right??) That is why i said I was confused as the psot begined with a public IP and ended up with a private IP . I felt few things were missing there to establish complete connection. 😀
  • durga ch
    durga ch
    Re: Need a Same IP Address for Internet? How to, Advantages, Disadvantages - Explaine

    ALl this will change when IPV6 is in!!!

    have you observed, few computers are already using IPV6.
    In IPV6, the Ip addresses are aquired statelessly (ie no DHCP needed) and infact deduced from the computers own MAC .that is one way , else DHCP is always there to assign.
  • PraveenKumar Purushothaman
    PraveenKumar Purushothaman
    Re: Need a Same IP Address for Internet? How to, Advantages, Disadvantages - Explaine

    Hey!!! I am still a big user of IPv4... Hope it shouldn't die as I am using all my servers in Windows XP SP3! 😔 Yes, no NAT or DHCP is required for IPv6 as there are a lot of space available in the addresses. 😀 And moreover, Windows Vista onwards, and Ubuntu 10.x onwards, the systems are capable of both IPv4 and IPv6! 😁

    Still I have a query! How to access sites running in IPv6 with their IP Address? In case of mine, it is like #-Link-Snipped-# but what about an IPv6 Site? Is it like #-Link-Snipped-# ??? 😲
  • durga ch
    durga ch
    Re: Need a Same IP Address for Internet? How to, Advantages, Disadvantages - Explaine

    ok.. we will still be having DNS right??
    and address such as #-Link-Snipped-# can be shortend but not to a complete extent #-Link-Snipped-#
    is ok.

    Actually your post got me thinking- is it possible to assign a public Ip through DHCP? I have been thinking in terms of a LAN where DHCP assigns only 192.x.x.x range (for calss c ofcourse), but geniuely speaking, can DHCP really go beyond private and assign public Ip for a machine within a network .

    Thsi is getting onto me now and I am at work, and have to do some serious GAP analysis and some flowsequences 😔 and I can tput my mind into it. Praveen how many Public Ips did you get from your ISP???
  • PraveenKumar Purushothaman
    PraveenKumar Purushothaman
    Re: Need a Same IP Address for Internet? How to, Advantages, Disadvantages - Explaine

    I got many public IPs in the range of 122.164.143.XXX
  • durga ch
    durga ch
    Re: Need a Same IP Address for Internet? How to, Advantages, Disadvantages - Explaine

    did you say your ISP gave you multiple pulbic IPs, seeing that you are a consumer customer and IPV4 are scare, I am amused that you got them. lucky you!
    Ok, back to the question - I will have to go back to my home and check out few things before i can comnet about DHCP assigning public IPs. The other screenshot what you provided is for statis IP, i dont think it is specifically for DHCP reservations. The difference between both being- statis IP is for you, even if you are not using it, while reservation justs reserves it for you when you are online.

    Thanks for the post. looks like i have some study to do
  • PraveenKumar Purushothaman
    PraveenKumar Purushothaman
    Re: Need a Same IP Address for Internet? How to, Advantages, Disadvantages - Explaine

    Yeah, before that let me put in front a disclaimer, if you are not knowing what you are doing, please don't do it... Coz, I had a serious issue implementing what I said!!! 😔
  • ShrinkDWorld
    ShrinkDWorld
    Re: Need a Same IP Address for Internet? How to, Advantages, Disadvantages - Explaine

    Thanks praveenscience.
    Your work is really hard, & this is very difficult to understand for me!!
  • PraveenKumar Purushothaman
    PraveenKumar Purushothaman
    Re: Need a Same IP Address for Internet? How to, Advantages, Disadvantages - Explaine

    Thanks for the motivation Gaurav... I will try to post more beginners oriented posts and will try mentioning the difficulty and understanding level too... 😀
  • ShrinkDWorld
    ShrinkDWorld
    Re: Need a Same IP Address for Internet? How to, Advantages, Disadvantages - Explaine

    beginners oriented posts
    Thanks in advance!
    I really need it.

You are reading an archived discussion.

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