[145654] in North American Network Operators' Group
How Skype uses the network [was: News item: Blackberry services down
daemon@ATHENA.MIT.EDU (Patrick W. Gilmore)
Fri Oct 14 15:13:07 2011
From: "Patrick W. Gilmore" <patrick@ianai.net>
In-Reply-To: <4E97738B.1010508@matthew.at>
Date: Fri, 14 Oct 2011 15:11:15 -0400
To: NANOG list <nanog@nanog.org>
Errors-To: nanog-bounces+nanog.discuss=bloom-picayune.mit.edu@nanog.org
On Oct 13, 2011, at 7:26 PM, Matthew Kaufman wrote:
> On 10/13/11 3:30 PM, Patrick W. Gilmore wrote:
>> In fact, Skype, just as a for instance, is worse on hotel wifi as =
launching the app on a laptop makes you a middle node for some =
conversations.=20
>=20
> Per the Skype IT administrator guide, a Skype node will not become a =
supernode unless it has a public IP address and meets the memory, =
bandwidth, and uptime requirements. It will not become a relay node =
unless it has a public IP address and is directly reachable from the =
Internet.
>=20
> It is very unlikely that launching the Skype app on a laptop on hotel =
wi-fi would meet these requirements.
In the last 5 seconds, without touching Skype or having any active voice =
or chat sessions open, my computer has had communication with 14 IP =
addresses. Here is a sample of some:
TiggerAir-i7-2:~ patrick$ host 94.193.99.152
152.99.193.94.in-addr.arpa domain name pointer =
94-193-99-152.zone7.bethere.co.uk.
TiggerAir-i7-2:~ patrick$ host 78.90.137.244
Host 244.137.90.78.in-addr.arpa. not found: 3(NXDOMAIN)
TiggerAir-i7-2:~ patrick$ host 175.129.63.150
150.63.129.175.in-addr.arpa domain name pointer =
KD175129063150.ppp-bb.dion.ne.jp.
TiggerAir-i7-2:~ patrick$ host 218.190.29.244
Host 244.29.190.218.in-addr.arpa. not found: 3(NXDOMAIN)
TiggerAir-i7-2:~ patrick$ host 128.2.238.215
215.238.2.128.in-addr.arpa domain name pointer =
ETC-NALZAYER.ETC.CMU.EDU.
TiggerAir-i7-2:~ patrick$ host 212.187.172.66
Host 66.172.187.212.in-addr.arpa. not found: 3(NXDOMAIN)
Those do not look like Skype servers. I guess it is possible everyone =
in my contact list is somehow pinging me, but that seems a little bit =
silly.
My IP address is 172.30.19.19, hopefully I do not have to explain that =
this is not a "public IP address". I have been online a few minutes, so =
unless their uptime requirements are about the same as a regular phone =
call, it is too short. I will admit, I have plenty of bandwidth =
available, though.
In short, while they can claim my laptop is not being used as a =
supernode or relay, Skype is still randomly talking to a slew of IP =
addresses. Anyone know what Skype is doing?
>> Does Skype on $HANDHELD have the same property?=20
> Not as far as I know, for the obvious reason that handheld devices =
have network connections that are suboptimal for this.
The above happens to my laptop when I am on 3G / EDGE, even when I have =
a 10-net address. In fact, one of the first things I do on 3G is kill =
Skype because it noticeably increases my network performance.
I haven't checked on my iPhone 'cause I don't have things like tcpdump & =
little snitch.
--=20
TTFN,
patrick
