siraj.shaikh at gmail.com
Thu Feb 21 12:07:11 UTC 2008
On 29/01/2008, Olivier Nicole <on at cs.ait.ac.th> wrote:
> > 1) is there an upper limit to configuring a number of alias addresses?
> I have a machine with 200+ IP without any problem.
> > 2) if an interface is configured with an alias address, then what
> > address is shown on the traffic leaving this interface? So, for
> > example, if I were to ping this machine on its primary address, I
> > expect to get a response from the primary address of the interface.
> > What happens if I ping an alias address, would I get a response from
> By default exiting traffic is using the primary address (the one
> defined with no keyword alias in the ifconfig). I think there is a way
> to choose the exiting IP.
> When a paket is responding, it use the same IP that was used in the
> query (else any firewall would be confused in the way).
> > 3) In the above scenario, all traffic leaving the interface
> > (regardless of the source IP on it) will have the same MAC address
> > (the one of the interface) - is that right?
> Right except maybe some NIC that allow several MAC addresses? That
> could be used in hi availability?
> > 4) Does anyone know if there are there any other network
> > characteristics or behaviour by which we can distinguish a machine
> > having more than one IP address (primary plus alias) configued on one
> > of its interface?
> Once you cross a router, you don't see the MAC of the machine anymore,
> MAC is local to your LAN anyway.
One last thing I wanted to know (sorry to email after a long delay),
in order for me to add aliases that I want to remain configured on the
machine at every boot, I can simply add, for exmaple, the following
lines to the rc.conf file?
ifconfig_ed0_alias0="inet 127.0.0.251 netmask 0xffffffff"
ifconfig_ed0_alias1="inet 127.0.0.252 netmask 0xffffffff"
ifconfig_ed0_alias2="inet 127.0.0.253 netmask 0xffffffff"
Just want to know, as I want to configure about 253 addresses as an
alias on a single machine (along with the primary address, this will
be 254 address, a whole C-class subnet) - and would like these entries
to hold when I boot. Also, is there any shortcut to adding a range of
net/host address or would I have to add a line for each address?
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