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From: Ben Greear <greearb@candelatech.com>
To: netdev <netdev@vger.kernel.org>
Subject: Why is gre0 auto-created, and can we fix it?
Date: Tue, 03 Jan 2012 11:49:50 -0800	[thread overview]
Message-ID: <4F035BDE.5060409@candelatech.com> (raw)

While trying to figure out why 'gre0' doesn't
go away properly in my application, I noticed that
it is auto-created if you just run 'ifconfig gre0'.
(Same thing happens if you use 'ip link show gre0')

As far as I can tell, no other interfaces are auto-created
in this manner.

If I cook up a patch to 'fix' this, would it be acceptable,
or are we stuck with the current behaviour for backwards-compat
reasons?

[root@lec2010-ath9k-1 lanforge]# rmmod ip_gre
[root@lec2010-ath9k-1 lanforge]# ip link show
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 16436 qdisc noqueue state UNKNOWN
     link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000
     link/ether 00:90:0b:13:ed:ea brd ff:ff:ff:ff:ff:ff
3: eth1: <NO-CARRIER,BROADCAST,MULTICAST,UP> mtu 1500 qdisc pfifo_fast state DOWN qlen 1000
     link/ether 00:90:0b:13:ed:eb brd ff:ff:ff:ff:ff:ff
[root@lec2010-ath9k-1 lanforge]# ifconfig gre0
gre0      Link encap:UNSPEC  HWaddr 00-00-00-00-00-00-01-00-00-00-00-00-00-00-00-00
           NOARP  MTU:1476  Metric:1

[root@lec2010-ath9k-1 lanforge]# ip link show
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 16436 qdisc noqueue state UNKNOWN
     link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000
     link/ether 00:90:0b:13:ed:ea brd ff:ff:ff:ff:ff:ff
3: eth1: <NO-CARRIER,BROADCAST,MULTICAST,UP> mtu 1500 qdisc pfifo_fast state DOWN qlen 1000
     link/ether 00:90:0b:13:ed:eb brd ff:ff:ff:ff:ff:ff
76: gre0: <NOARP> mtu 1476 qdisc noop state DOWN
     link/gre 0.0.0.0 brd 0.0.0.0
[root@lec2010-ath9k-1 lanforge]# ifconfig tap0
tap0: error fetching interface information: Device not found

Thanks,
Ben

-- 
Ben Greear <greearb@candelatech.com>
Candela Technologies Inc  http://www.candelatech.com

             reply	other threads:[~2012-01-03 19:49 UTC|newest]

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2012-01-03 19:49 Ben Greear [this message]
2012-01-03 19:59 ` Why is gre0 auto-created, and can we fix it? David Miller
2012-01-03 20:03   ` Ben Greear
2012-01-03 20:11     ` David Miller
2012-01-21 17:39     ` Krzysztof Halasa
2012-01-21 17:48       ` Ben Greear
2012-01-21 18:40         ` David Miller
2012-01-22 16:48           ` Ben Greear
2012-01-22 19:14             ` David Miller
2012-01-22 19:43               ` Stephen Hemminger
2012-01-22 21:00               ` Ben Greear

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