Jails and IP Aliasing

Jason Morgan jwm-freebsd-questions at sentinelchicken.net
Mon Jul 7 17:55:44 UTC 2008


Hello,

On 2008.07.07 09:51:33, David Allen wrote:
> Unless I'm losing my mind, I'm encountering what seems to yet another
> gotcha with jails.  The following has been dumbed down for clarity and
> brevity.
> 
> ---------------------------------------------------------------------
> # hostname
> jailhost.example.org
> 
> # host jailhost
> jailhost.example.org has address 10.0.1.2
> 
> # ifconfig fxp0
> fxp0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> metric 0 mtu 1500
>         options=b<RXCSUM,TXCSUM,VLAN_MTU>
>         ether 00:07:e9:c8:2e:32
>         inet 10.0.1.2 netmask 0xffffff00 broadcast 10.0.1.255
>         inet 10.0.1.3 netmask 0xffffffff broadcast 10.0.1.3
>         inet 10.0.1.4 netmask 0xffffffff broadcast 10.0.1.4
>         media: Ethernet autoselect (100baseTX <full-duplex>)
>         status: active

This is the output for my jail interface. Notice that your jail
aliases are broadcasting on the jail's IP. I don't know if this is an
issue or not (my jails run on i386 FBSD 6.3), but it's something to
look at. How are you setting the aliases?

sk0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> mtu 1500
     options=b<RXCSUM,TXCSUM,VLAN_MTU>
     inet 10.0.0.1 netmask 0xffffff00 broadcast 10.0.0.255
     inet 10.0.0.101 netmask 0xffffff00 broadcast 10.0.0.255
     inet 10.0.0.201 netmask 0xffffff00 broadcast 10.0.0.255
     ether xx:xx:xx:xx:xx:xx
     media: Ethernet autoselect (1000baseTX <full-duplex,flag0,flag1>)
     status: active

Cheers,
~Jason


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