NetBSD Problem Report #21633

Received: (qmail 10519 invoked by uid 605); 21 May 2003 06:09:02 -0000
Message-Id: <200305210608.h4L68wI06978@mofo.grunta.com>
Date: Wed, 21 May 2003 16:08:58 +1000 (EST)
From: grant@netbsd.org
Sender: gnats-bugs-owner@netbsd.org
To: gnats-bugs@gnats.netbsd.org
Subject: packets originate from previous IP address after changing it
X-Send-Pr-Version: 3.95

>Number:         21633
>Category:       kern
>Synopsis:       packets originate from previous IP address after changing it
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    kern-bug-people
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Wed May 21 06:10:01 +0000 2003
>Closed-Date:    
>Last-Modified:  Wed May 28 01:53:00 +0000 2003
>Originator:     grant beattie
>Release:        NetBSD 1.6T
>Organization:
>Environment:
NetBSD u10 1.6T NetBSD 1.6T (GENERIC) #0: Sun May 18 20:52:48 EST 2003  autobuild@mofo:/data1/netbsd/autobuild/current/obj.sparc64/sys/arch/sparc64/compile/GENERIC sparc64
Architecture: sparc64
Machine: sparc64
>Description:
after killing dhclient and changing the IP address of the hme0 interface,
I noticed packets still continue to originate from the old address.
unsurprisingly, those connections fail. connections to the new address
work fine.

the machine has been left in this state overnight and the problem still
persists.

tcpdump shows packets originating from the old address, ifconfig reports
the new address correctly.

15:46:14.523970 10.129.2.226.65143 > 203.8.183.1.domain:  53701+ AAAA? ftp.tuwien.ac.at. (34)
15:46:19.530169 10.129.2.226.65142 > 203.8.183.1.domain:  53701+ AAAA? ftp.tuwien.ac.at. (34)
15:46:29.540147 10.129.2.226.65141 > 203.8.183.1.domain:  53701+ AAAA? ftp.tuwien.ac.at. (34)
15:46:49.550272 10.129.2.226.65140 > 203.8.183.1.domain:  53701+ AAAA? ftp.tuwien.ac.at. (34)

u10: {71} ifconfig hme0
hme0: flags=8b63<UP,BROADCAST,NOTRAILERS,RUNNING,PROMISC,ALLMULTI,SIMPLEX,MULTICAST> mtu 1500
        address: 08:00:20:9f:0f:17
        media: Ethernet autoselect (100baseTX full-duplex)
        status: active
        inet 10.129.2.22 netmask 0xffff0000 broadcast 10.129.255.255
        inet6 fe80::a00:20ff:fe9f:f17%hme0 prefixlen 64 scopeid 0x1

the workaround is to reboot.

>How-To-Repeat:
change the IP address of an interface, notice that packets originate
from the old address.
>Fix:
unknown.
>Release-Note:
>Audit-Trail:

From: grant beattie <grant@netbsd.org>
To: gnats-bugs@gnats.netbsd.org
Cc:  
Subject: Re: kern/21633: packets originate from previous IP address after changing it
Date: Wed, 21 May 2003 17:54:39 +1000

 > after killing dhclient and changing the IP address of the hme0 interface,
 > I noticed packets still continue to originate from the old address.
 > unsurprisingly, those connections fail. connections to the new address
 > work fine.

 the interface was not down/up'd after changing the address, however
 that doesn't fix it.

 > u10: {71} ifconfig hme0
 > hme0: flags=8b63<UP,BROADCAST,NOTRAILERS,RUNNING,PROMISC,ALLMULTI,SIMPLEX,MULTICAST> mtu 1500
 >         address: 08:00:20:9f:0f:17
 >         media: Ethernet autoselect (100baseTX full-duplex)
 >         status: active
 >         inet 10.129.2.22 netmask 0xffff0000 broadcast 10.129.255.255
 >         inet6 fe80::a00:20ff:fe9f:f17%hme0 prefixlen 64 scopeid 0x1

 packets destined for the local network come from this address.

 anything destined for outside the local network incorrectly originates
 from the old address, .226. the box no longer responds to arp
 broadcasts for this address.


From: grant beattie <grant@netbsd.org>
To: gnats-bugs@gnats.netbsd.org
Cc:  
Subject: Re: kern/21633: packets originate from previous IP address after changing it
Date: Wed, 21 May 2003 19:10:23 +1000

 at Martin's suggestion, I built a kernel without IPv6. the problem
 persists.

From: itojun@iijlab.net
To: grant@netbsd.org
Cc: gnats-bugs@gnats.netbsd.org
Subject: Re: kern/21633: packets originate from previous IP address after changing it 
Date: Thu, 22 May 2003 15:45:36 +0900

 >>Synopsis:       packets originate from previous IP address after changing it

 	this is a known "feature" of 4.4BSD - routing entries keep source
 	address selection results (rt_ifa) and interface address list is not
 	consulted on source address selection.

 itojun

From: grant beattie <grant@netbsd.org>
To: itojun@iijlab.net
Cc: gnats-bugs@gnats.netbsd.org
Subject: Re: kern/21633: packets originate from previous IP address after changing it
Date: Wed, 28 May 2003 11:47:07 +1000

 On Thu, May 22, 2003 at 03:45:36PM +0900, itojun@iijlab.net wrote:

 > >>Synopsis:       packets originate from previous IP address after changing it
 > 
 > 	this is a known "feature" of 4.4BSD - routing entries keep source
 > 	address selection results (rt_ifa) and interface address list is not
 > 	consulted on source address selection.

 the upshot of this is that I must reboot this box 16 times to test 16
 IP address ranges using the same interface.

 The behaviour I'm observing now is slightly different (packets originate
 from the correct address, but it does not reply to arp broadcasts for
 same address). If I reboot and configure the interface with the
 desired address from scratch, it works as expected.

 I must consider it a bug to not be able to properly change IP
 addresses on the fly. rebooting upon changing an IP address is
 unacceptable.

 this behavior does not exist in FreeBSD 5.0.

 g.


From: itojun@iijlab.net
To: grant beattie <grant@netbsd.org>
Cc: gnats-bugs@gnats.netbsd.org
Subject: Re: kern/21633: packets originate from previous IP address after changing it 
Date: Wed, 28 May 2003 10:52:19 +0900

 >> 	this is a known "feature" of 4.4BSD - routing entries keep source
 >> 	address selection results (rt_ifa) and interface address list is not
 >> 	consulted on source address selection.
 >the upshot of this is that I must reboot this box 16 times to test 16
 >IP address ranges using the same interface.

 	you don't need to, you just need to flush routees.

 itojun
>Unformatted:

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