Vodafone Broadband Ping Issue

Forums › One New Zealand (including Vodafone, WxC, Farmside) › Vodafone Broadband Ping Issue

snot

3 posts

Wannabe Geek

#29827 20-Jan-2009 18:01

I am new to this forum, so apologies now if I get procedures a bit muddled.
My issue is as a vodafone broadband user running a small business network from home on an IP range of 10.0.0.0, why can I ping and get a response on 192.168.1.1. If I remotely logon to a vodafone broadband clients site and ping any number within that range I get a similar response, but with xtra, clear or other broadband provided clients I get no response, which is what I'd expect. It concerns me a bit, as I am sure I should not get a reply when I or my clients are not on that local IP range. The ping reply is positive only from Vodafone Broadband customers.
Anyone got any suggestions.

PenultimateHop

637 posts

Ultimate Geek

Trusted

#190888 20-Jan-2009 19:55

Because there is a device in the Vodafone network with the IP address 192.168.1.1 configured on it. I don't see a problem with this (it's not best practice perhaps, but there is nothing inherently evil about it).

snot

3 posts

Wannabe Geek

#190993 21-Jan-2009 10:47

Thanks for this PenultimateHop but I disagree. My understanding is that IP ranges such as 192.168.1.X are closed to the internet. If I am not on this range locally then I should get no reply after the Ping. I don't if I turn off my router.
I am not suggesting there is anything evil about this. It just should not be possible.

PenultimateHop

637 posts

Ultimate Geek

Trusted

#191032 21-Jan-2009 12:38

snot: Thanks for this PenultimateHop but I disagree. My understanding is that IP ranges such as 192.168.1.X are closed to the internet. If I am not on this range locally then I should get no reply after the Ping. I don't if I turn off my router.
I am not suggesting there is anything evil about this. It just should not be possible.

Unfortunately your understanding is wrong. RFC1918 addressing (which includes 192.168/16) is indeed reserved for private network use, however there is nothing which prohibits it being used by an ISP, which is effectively a private network that is connected to the Internet via a gateway or series of gateways.

As you are connected to what is effectively Vodafone's private network, you are able to reach the device in their network which is numbered as 192.168.1.1. It's not uncommon, not unusual, but probably not Best Common Practice (BCP), which is all that stops RFC1918 addressing leaking between autonomous systems on the Internet. In fact, it's pretty common for RFC1918 addresses to leak in the global DFZ...

snot

3 posts

Wannabe Geek

#191035 21-Jan-2009 12:45

Ok. Thanks for this and for taking the time to reply. Much appreciated.

richms

28178 posts

Uber Geek

Trusted

Lifetime subscriber

#191124 21-Jan-2009 19:08

There was a period when telecom used private addresses on the network between adsl customers and the internet, so if there was any issues with must fragment etc (common because of the stupid PPPoA used) then the ICMP went out with the private IP on it, which any sane firewall admin has set their internet facing servers to discard since its usually used internally and should never be seen coming in from the outside.

Richard rich.ms

PenultimateHop

637 posts

Ultimate Geek

Trusted

#191336 22-Jan-2009 16:36

richms: There was a period when telecom used private addresses on the network between adsl customers and the internet, so if there was any issues with must fragment etc (common because of the stupid PPPoA used) then the ICMP went out with the private IP on it, which any sane firewall admin has set their internet facing servers to discard since its usually used internally and should never be seen coming in from the outside.

PPPoA should not cause fragmentation-required messages as it will happily allow a 1500b packet through (the underlying transport is after all ATM!). PPPoE often caused this issue, due to 1500 byte Ethernet MTUs and the overhead required for PPP, however draft-ardberg resolved this one.

Most firewall admins block all ICMP anyway (which is stupid), and will break things far worse than RFC1918 sourced must-fragment messages.