Can't ping a GPRS-enabled laptop...

byrne_baby_byrn

Hi guys
I'm using a laptop with a Nokia D211 GPRS card. I'm able to connect to the net and ping other machines and I'm able to get the dynamically-assigned IP address that's given to me using ipconfig. When I ping this IP address from another machine I don't get any replies though!
Any ideas? I'm using an O2 pay-as-you-go SIM card, if that makes any difference. I have tried it with a pay-monthly SIM too but get the same problem.
Any help appreciated...
Jay

happydude13

What do you get if you go to somewhere like

www.whatismyip.com

Does this match the ipconfig output ?

byrne_baby_byrn

Thanks for the reply - looks like a handy site to know.
It returns the same IP address as ipconfig though...

parsi

When you connect using GPRS aren't you in a VPN tunnel to your ISP and maybe this is why you can't be pinged ?

tomk

Why do you need to ping the laptop? Are you running services on it that need to be accessed over the net?

Do you have a firewall on the laptop that could be blocking incoming ping requests?

byrne_baby_byrn

Hi tomk
Yeah, I'm doing some vehicle logistic research so basically I need to have an in-vehicle laptop that is network enabled. We use vehicle tracking boxes that log GPS positions to a fixed server, but for testing puposes I want the laptop to be the server... that's why I need to be able to receive incoming data!
Feel free to bounce around any ideas. I can get a work around but it would only complicate things to be honest - the less complexity, the less mistakes...
Cheers mate

byrne_baby_byrn

Hi parsi
I'd imagine that there is a VPN between the laptop and the ISP but the IPS doesn't seem to act as a proxy (whatismyip.com sees the laptops dynamically-assigned IP address and not a different proxy one). It could be that incoming ports are blocked, it could be that I need to somehow specify an O2 DNS or something like that, either way incoming connections seem to be getting lost or are being blocked.
If the VPN would make a difference can you let me know how?
Thanks for the post...

tomk

byrne_baby_byrn wrote:

that's why I need to be able to receive incoming data!

Do you particularly need to be able to ping? It could be that pings are blocked on the GPRS network, but that other traffic is OK - I've heard that this is the case with some ISPs.

Try some other type of connection - telnet, ftp, ssh, etc. Or try your actual application (sounds interesting, by the way).

happydude13

You could try to run nmap on the ip address.

You can configure it quite nicely to try all sorts
of stuff.

dublincastro

You might want to try a post paid (contract) sim and use the 'open.internet' APN as this allows unrestricted access unlike the 'internet' APN on contract and the 'pp.internet' APN that you are using on prepaid. This information only applies to the O2 network.