IP question

Can someone give me some information on the IP address 169.254.x.x. From what I understand, this IP address is given when the DHCP server cannot be found. I have a client who trying to connect to the city's free WiFi connection. From what he's telling me, I'm thinking he's too far away to get a decent signal. He's going to get close to the city and try it. But really I'm looking on more info on the 169.254.x.x IP address. Anyone have a link to some info?

In the meantime I'll be checking my favorsite site Google.

Find more posts tagged with

Free for TechExams community: Cybersecurity salary guide

Compare cert salaries and plan your next career move

Button

Comments

sprkymrk

That is the APIP range, Automatic Privat IP, that a MS client assigns to itself when there is no DHCP server available. You are probably correct in assuming he is too far to get a signal.

Sie

[Edit - What Sprkymrk said he just types faster

]

sprkymrk

Sie wrote:

[Edit - What Sprkymrk said he just types faster ]

Now THAT'S a first, me typing faster than someone....

JDMurray

Yup, if a Windows DHCP client doesn't receive a response from a DHCP server, Windows will eventually assign itself an Automatic Private IP Addressing (APIPA) address in the 169.254/16 network. This happens all the time with 802.11 wireless clients.

Private network
Automatic Private IP Addressing (APIPA)

TechJunky

Do they have DHCP disabled for the Wireless Interface so people dont leech off the connection?

Try using a 192.x.x.x, 10.x.x.x, or 172.x.x.x if you know the LAN IP Addressing.

blargoe

Or they're just out of IP addresses

JDMurray

TechJunky wrote:

Do they have DHCP disabled for the Wireless Interface so people dont leech off the connection?

Wireless networks that use DHCP will (or should) also use a Layer 2 authentication service. A wireless client will need to pass Layer 2 authentication before it can be assigned a Layer 3 network address. This prevents "leeching."

sprkymrk

I have a client who trying to connect to the city's free WiFi connection.

I would assume a city's free wi-fi would not have any layer 2 authentication. A subscription or fee-based wi-fi might, but that doesn't sound like the case here.

mrhaun03

The client told me the first 2 hours of connectivity are free. You would think that there'd be some sort of authentication. It seems it would be too easy to get around the 2 hour limit.

JDMurray

mrhaun03 wrote:

The client told me the first 2 hours of connectivity are free. You would think that there'd be some sort of authentication. It seems it would be too easy to get around the 2 hour limit.

You are probably required to sign in to the network using a Web-based interface, which then records the MAC address of your wireless NIC. This is how they keep track of the two-hour limit. This type of authentication is performed at Layer 7. The public hotspot access at Starbucks operates the same way (except for the "free connectivity" part).

mrhaun03

After your 2 hours are up, couldn't spoof your MAC address? Although, the average user probably isn't aware of a MAC address or how to change it.

JDMurray

mrhaun03 wrote:

After your 2 hours are up, couldn't spoof your MAC address? Although, the average user probably isn't aware of a MAC address or how to change it.

Yes, some wireless network drivers have a configuration menu with an option to enter the MAC address used by the adapter. It requires a reboot and a little book keeping to make sure that you don't re-use a previous MAC address. These days it's usually easier to just find a public hotspot that doesn't have a time limit.