Possible regression in ifconfig under7.0 - removes validdefault route

Jeremy Chadwick koitsu at FreeBSD.org
Mon Nov 17 13:11:58 PST 2008


On Mon, Nov 17, 2008 at 08:45:43PM -0000, Steven Hartland wrote:
> ----- Original Message ----- From: "Jeremy Chadwick" <koitsu at FreeBSD.org>
>> I can try to reproduce this if you'd like, on a VMware session.
>>
>> One case where the default route could be (I haven't checked) removed:
>> some NIC drivers in the past, when changing the "primary IP" (first IP
>> shown in ifconfig for an interface), would actually bring down the
>> entire interface (e.g. ifconfig XXX down) then back up again a second or
>> two later.  dmesg on your machine would be able to confirm whether or
>> not this is happening.
>
>
> Thanks Jeremy, no such down up here is show so I believe this is not
> the case, here anyway. The interface in question was em0 details:-
> em0: <Intel(R) PRO/1000 Network Connection Version - 6.7.3> port 
> 0xd400-0xd43f mem 0xfea60000-0xfea7ffff,0xfea40000-0xfea5ffff irq 23 at 
> device 8.0 on pci1
> em0: Ethernet address: 00:30:48:71:b6:b7
> em0: [FILTER]
>
> FreeBSD test 7.0-RELEASE FreeBSD 7.0-RELEASE #0: Sun Feb 24 19:59:52 UTC 
> 2008 root at logan.cse.buffalo.edu:/usr/obj/usr/src/sys/GENERIC  i386
>
> Would be most interested in the results of you vm test if you would
> be so kind.

No problem.  I'm testing on VMware Workstation 6.5.0 build 118116,
RELENG_7 amd64 (world/kernel dated 2008/10/23).


rc.conf (showing DHCP is not in use):

ifconfig_em0="inet 192.168.1.190 netmask 255.255.255.0"
defaultrouter="192.168.1.1"

em0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> metric 0 mtu 1500
        options=9b<RXCSUM,TXCSUM,VLAN_MTU,VLAN_HWTAGGING,VLAN_HWCSUM>
        ether 00:0c:29:0a:c9:37
        inet 192.168.1.190 netmask 0xffffff00 broadcast 192.168.1.255
        media: Ethernet autoselect (1000baseTX <full-duplex>)
        status: active

Destination        Gateway            Flags    Refs      Use  Netif Expire
default            192.168.1.1        UGS         0        0    em0
127.0.0.1          127.0.0.1          UH          0        0    lo0
192.168.1.0/24     link#1             UC          0        0    em0
192.168.1.1        link#1             UHLW        2        0    em0
192.168.1.51       00:30:48:d2:22:d0  UHLW        2       50    em0   1107


Command executed: ifconfig em0 inet 10.0.0.1 netmask 255.0.0.0
Aftermath:

em0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> metric 0 mtu 1500
        options=9b<RXCSUM,TXCSUM,VLAN_MTU,VLAN_HWTAGGING,VLAN_HWCSUM>
        ether 00:0c:29:0a:c9:37
        inet 10.0.0.1 netmask 0xff000000 broadcast 10.255.255.255
        media: Ethernet autoselect (1000baseTX <full-duplex>)
        status: active

Destination        Gateway            Flags    Refs      Use  Netif Expire
10.0.0.0/8         link#1             UC          0        0    em0
127.0.0.1          127.0.0.1          UH          0        0    lo0


Command executed: route add default 10.0.0.128
Aftermath:

Destination        Gateway            Flags    Refs      Use  Netif Expire
default            10.0.0.128         UGS         0        0    em0
10.0.0.0/8         link#1             UC          0        0    em0
10.0.0.128         link#1             UHLW        2        0    em0
127.0.0.1          127.0.0.1          UH          0        0    lo0

Command executed: ifconfig em0 inet 10.10.10.10 netmask 255.0.0.0
Aftermath:

em0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> metric 0 mtu 1500
        options=9b<RXCSUM,TXCSUM,VLAN_MTU,VLAN_HWTAGGING,VLAN_HWCSUM>
        ether 00:0c:29:0a:c9:37
        inet 10.10.10.10 netmask 0xff000000 broadcast 10.255.255.255
        media: Ethernet autoselect (1000baseTX <full-duplex>)
        status: active

Destination        Gateway            Flags    Refs      Use  Netif Expire
10.0.0.0/8         link#1             UC          0        0    em0
127.0.0.1          127.0.0.1          UH          0        0    lo0


Summary: confirmed.  Above two tests show that even if changing the IP
to something else within the same network block, the default route is
removed and not put back.

This is pretty major, if you ask me.

-- 
| Jeremy Chadwick                                jdc at parodius.com |
| Parodius Networking                       http://www.parodius.com/ |
| UNIX Systems Administrator                  Mountain View, CA, USA |
| Making life hard for others since 1977.              PGP: 4BD6C0CB |



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