Mobile ip address

shamrock2004

Hi there. I am an O2 customer and using my android phone, I can connect to the internet over 3G - all is hunky dory.

When I go to a website that shows my ip address, I see a routable IP address, as I expected.

What I need to know however, is if this IP address is the result of NAT? In other words, would this IP address be the address of a gateway? Or, is this IP address a routable IP address that has been assigned to me by O2 on a lease basis, similar to DHCP. Ultimately, the reason I am asking, is that I have built a simple java class on my android (ServerSocket) that is to accept TCP connections from another android device, over 3G that is on Vodafone. It won't accept the connection. It's not a coding issue. I believe it's related to the setup of the telco (O2). Is anyone aware If I would be able to initiate a connection from my android on O2 to another android on Vodafone over 3G? As mentioned, this is not a coding issue. I'm just interested in the network side of things here.

Many thanks indeed.
Ned

swampgas

shamrock2004 wrote: »

Hi there. I am an O2 customer and using my android phone, I can connect to the internet over 3G - all is hunky dory.

When I go to a website that shows my ip address, I see a routable IP address, as I expected.

What I need to know however, is if this IP address is the result of NAT? In other words, would this IP address be the address of a gateway? Or, is this IP address a routable IP address that has been assigned to me by O2 on a lease basis, similar to DHCP. Ultimately, the reason I am asking, is that I have built a simple java class on my android (ServerSocket) that is to accept TCP connections from another android device, over 3G that is on Vodafone. It won't accept the connection. It's not a coding issue. I believe it's related to the setup of the telco (O2). Is anyone aware If I would be able to initiate a connection from my android on O2 to another android on Vodafone over 3G? As mentioned, this is not a coding issue. I'm just interested in the network side of things here.

Many thanks indeed.
Ned

Just an idea - can you ping the IP address? If you can, turn off your phone, now can you ping the IP address? If it still pings, you are definitely NAT'ed.

shamrock2004

Hi there

Thanks for the reply.

No, I cannot ping the other IP address. I have a feeling that ICMP may not be enabled.

Any other suggestions welcomed. Would it be worth contacting O2? Would they be able to field these type of questions?

thanks indeed

RichieD

shamrock2004 wrote: »

Hi there

Thanks for the reply.

No, I cannot ping the other IP address. I have a feeling that ICMP may not be enabled.

Any other suggestions welcomed. Would it be worth contacting O2? Would they be able to field these type of questions?

thanks indeed

Im just guessing but they must use some form of NAT. i.e. you have a local address on the 02 3G network and its translated to an 02 global address for when you access the web.

So to answer your question, its probably a gateway.

shamrock2004

RichieD wrote: »

Im just guessing but they must use some form of NAT. i.e. you have a local address on the 02 3G network and its translated to an 02 global address for when you access the web.

So to answer your question, its probably a gateway.

Yeah I had figured as much. Pity it's so difficult to find out for certain...

Thanks again
Ned

Johnboy1951

I wonder if it is possible to run something like DynDNS on the phone .... and if it would work in that situation ......

cargo

Fairly certain they use NAT on their general browsing 3G APN however if you were using a data APN you may not have this issue.

Cant be sure as I'm on VF and they have different APN's allowing different services on the APN i.e. live = web & HS/ISP = data

MrO

download and install network info II from the market place, it will most likely tell you what you need to know

Captain Commie

different network, but i use 3 on my samsung tab and noticed that they use NAT.

I found this out by installing the speedtest.net app for android, on the settings page it lists your IP, both the Internal and External, with the Internal being the one that 3 give me on their network and the external one being the address that my connection is NAT'd through.

I imagine that this will be the same for all the network providers as i doubt they would have a pool of IP's large enough to give one per person, just wait till IPv6 is properly rolled out, then ur device can have as many IP's as you want it to have (within reason)

Shane O' Malley

If i remember correctly O2 always used a NAT.

3 Used to use a gateway and proxy but had so many problems they had to pull out that system. (IE IP address kept getting blacklisted because of spam from other users.