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Thread: IPhone DHCP w/ 196.254.x.x scope

  1. #1
    Thumbs down IPhone DHCP w/ 196.254.x.x scope
    Wrong Forum Dunno? Appols if so...

    Seems like the iphone does not like DHCP servers using an IP address scope of 169.254.x.x Have also heard that this is the same for other MAC OS versions?

    Anyone confirm / deny this?

    I know:
    169.254.x.x /16 is a strange scope for a DHCP server buts its a valid address.
    A 169.254.x.x IP is auto majik alllocated if no DHCP server available

  2. #2
    Livin the iPhone Life Eurisko's Avatar
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    Quote Originally Posted by youcrazy View Post
    Wrong Forum Dunno? Appols if so...

    Seems like the iphone does not like DHCP servers using an IP address scope of 169.254.x.x Have also heard that this is the same for other MAC OS versions?

    Anyone confirm / deny this?

    I know:
    169.254.x.x /16 is a strange scope for a DHCP server buts its a valid address.
    A 169.254.x.x IP is auto majik alllocated if no DHCP server available
    169.254.x.x is a "dummy" IP address and not specific to the iPhone. If your WiFi connection CAN connect to a server, but CAN'T get an IP from that server, the iPhone will assign itself 169.254.x.x

    This will also happen with regular desktop and laptop computers using wireless connections.
    Get "iPod & iTunes for Dummies", it'll change your life.

  3. #3
    Retired Moderator bhz1's Avatar
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    Quote Originally Posted by Eurisko View Post
    169.254.x.x is a "dummy" IP address and not specific to the iPhone. If your WiFi connection CAN connect to a server, but CAN'T get an IP from that server, the iPhone will assign itself 169.254.x.x

    This will also happen with regular desktop and laptop computers using wireless connections.
    I have been a lurker here since Spetember and this is my first post. First of all hello and thanks for all the great info on jailbreak, etc... My iPhone came OTB with 1.0.2 and having had come form a fully modded moto v3i (modded to run EDGE) I discovered this forum in the hopes of finding more modding fun. I held off jailbreaking until 1.1.1 came out. I mainly wanted text edit and ability to send files/pictures via email. Oh, and games that were not webapps. Once you try jailbreak, you'll never go back! Now running a jailbroken 1.1.2. Haven't unlocked since I run on ATT but thinking about it so that i can use foreign SIMs when traveling. Not intending to hijack the thread here so, back to the topic.

    I have had this happen quite frequently with my laptop. I have a combination wired/ wifi network- 4 desktops and an xbox 360 on the wired router and my laptop, iphone and husband's Blackberry on the wifi. About once a week (interestinly usually on Saturday nights) the laptop will not be able to get an IP and i will get the 169.254.x.x IP. Very annoying as the only way it seems to be fixed is if I reset the security on the wifi, which is a pain because then i have to reset all the passwords on the iphone and Blackberry as well.

    After researching this, I read where it helps if you assign static IP's to all your networked devices, but I haven't tried that yet.

  4. #4
    i get this often and it usually occurrs because I switch between different wifi networks (hotspots with DHCP).

    What I do to overcome this is regularly reset my network settings.
    Settings->General->Reset->Reset Network Settings

    Of course if you have set up any networks with static IP settings or WEP/WPA keys these will be wiped out and you'll have to reinsert them.

  5. #5
    Retired Moderator bhz1's Avatar
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    What is odd is that I never have this issue (dummy IP assigned) with my iPhone on the home wifi but I do with my laptop that I've had for 2 years that only rarely leaves home.

    On the other hand, i find that the iPhone has more trouble connecting to wifi hotspots. What I have determined is that if netstumbler is showing a signal strentgth of less than 15, the iPhone will show as connected but safari or anything will not work. I have to shut wifi off otherwise the phone will not default to EDGE. If there is a strong signal, no problems.

  6. #6
    Quote Originally Posted by Eurisko View Post
    169.254.x.x is a "dummy" IP address and not specific to the iPhone. If your WiFi connection CAN connect to a server, but CAN'T get an IP from that server, the iPhone will assign itself 169.254.x.x
    This will also happen with regular desktop and laptop computers using wireless connections.
    OK ..Yeah I know what Link-local addresses (or Zeroconf) are...

    Link-local addresses (or Zeroconf)
    For those who dont know If your client (wifi device, laptop, blackberry +wifi, server whatever).. has problems communicating / finding the DHCP server (that server could be a router, other network device, server whatever) on your network (wifi or lan) it will basically just time out, give up just allocate its own IP address. But not just any, it will come from a range -> 169.254.x.x with subnet 255.255.0.0 and no gateway of course. Now this normal!!! call

    My Problem
    What I am talking about is where a DHCP server is setup with a scope (pool of IP addresses that it gives out to clients) ..this happens to be the same range of 169.254.x.x. Now this should and does work ok...

    ..But this iphone doesnt seemto like this range. Being a MAC novice I wonder if others have seen / heard about this? on MACs or iphones..

    Notes
    Normally people setup their internal networks and DHCP scops or zones using RC1918 address or private address. These are:
    10.0.0.0 10.255.255.255
    172.16.0.0 172.31.255.255
    192.168.0.0 192.168.255.255

    I know this is different but it should work.

    Hopefully this makes more sense now.. & I'll stop using the bold

  7. #7
    i get this problem... and it happens only when i'm trying to access public hotspots
    and when i get this problem... it happens to both my iphone and macbook

    with my macbook, i can try to restart my wifi manually repeatedly.. and by luck.. i will get an IP address assigned and I can go online. however, even after i am able to go online with my macbook, it's extremely difficult for my iphone.

    sometimes, i can just turn on airplane mode for a few seconds, turn it off and turn on wifi.. and it works.. most of the time... i just get the 2 numbers above, and everything else are empty.

    do inform me if anyone knows of a better solution.. rather than rigorously trying to connect and zapping my iphone battery dry in the process

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