Re: No ifconfig
On Monday 21 August 2017 13:19:11 Christian Seiler wrote:
> On 08/21/2017 07:07 PM, Gene Heskett wrote:
> > On Monday 21 August 2017 12:11:38 Christian Seiler wrote:
> >> On 08/21/2017 05:03 PM, Gene Heskett wrote:
> >> iface eth0 inet static
> >> address 192.168.0.1/24
> >> address 192.168.0.42/24
> >> address 10.5.6.7/8
> >>
> >> This will work, and it will assign all IPs to the interface (the
> >> first one being the primary and the source IP of outgoing packets
> >> where the program doesn't explicitly bind anything). And "ip a"
> >> will show all three addresses, but "ifconfig -a" will only show the
> >> first.
> >
> > Ok, but then how do you differentiate between the addresses without
> > the :1 [:2 etc] notation?
>
> I don't understand the question? Where do you want to specify an
> address? When removing the address you just say "remove address XYZ
> from interface ABC".
>
> > It doesn't seem right that is would bang all the assigned addresses
> > with duplicate data.
>
> I don't get what you mean here. What is duplicate? If you open an
> outgoing connection by default the primary (first) IP that matches
> the outgoing subnet will be used as the source IP for that
> connection - but a program can override that by binding the socket
> to any of the other IPs of that interface.
>
I'll have to study up on this "binding" and how its done.
> In the above example: any connection to 192.168.0.23 will by default
> carry the source IP 192.168.0.1, and any connection to 10.1.1.1 will
> by default carry the source IP 10.5.6.7. An application can create
> an outgoing connection with source IP 192.168.0.42 by explicitly
> binding the socket to that IP before making the connection.
>
> Which is kind of similar to alias interfaces: with alias interfaces
> the route metric of the alias interfaces relative to each other
> defines what IP will be used by default, but again it is possible
> for an application to override that by binding the socket to a
> specific IP address.
>
> And incoming connections are trivial anyway in these setups.
>
> From the point of view of applications that just use the socket layer
> (and don't care about network interface names) the system will react
> in the same way whether you use multiple addresses per interface or
> whether you use alias interfaces. The main differences are in how it
> is configured and how the kernel code works.
>
> Regards,
> Christian
This has been an enlightening discussion, Christian, thank you for your
time.
Cheers, Gene Heskett
--
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