[LARTC] iproute2 and ethX:X subdevices

[LARTC] iproute2 and ethX:X subdevices

[Alan Ford]

Hi,

Quick question -- is it possible to create eth0:0 - style psuedo-devices
using the 'ip' tool?

I see they recognise them when using 'ip addr show':
5: eth2: <BROADCAST,MULTICAST,ALLMULTI,UP> mtu 1500 qdisc pfifo_fast qlen 1000
    inet 192.168.0.1/24 brd 192.168.0.255 scope global eth2:0

But I can't see a way of creating them. Is it possible?

(I know somebody may say "why would I want to" -- it's just for neatness,
so that people using 'ifconfig' can still see all the addresses in use.)

Thanks,
-- 
Alan Ford * alan@whirlnet.co.uk 
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Re: [LARTC] iproute2 and ethX:X subdevices

[Angus D Madden]

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Alan Ford, Tue, Feb 03, 2004 at 05:41:06PM +0000: 
> Hi,
> 
> Quick question -- is it possible to create eth0:0 - style psuedo-devices
> using the 'ip' tool?
> 

ip addr add 10.0.0.1/24 dev eth0 label eth0:0



g



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Re: [LARTC] iproute2 and ethX:X subdevices

[Martin A. Brown]

Alan,

 : Quick question -- is it possible to create eth0:0 - style
 : psuedo-devices using the 'ip' tool?

They aren't really "pseudo-devices", but we understand what you mean.  In
the days prior to the iproute2 tools, when a device would have one
interface, which would have one IP address, they were called IP aliases.

 : I see they recognise them when using 'ip addr show':
 :
 : 5: eth2: <BROADCAST,MULTICAST,ALLMULTI,UP> mtu 1500 qdisc pfifo_fast qlen 1000
 :     inet 192.168.0.1/24 brd 192.168.0.255 scope global eth2:0
 :
 : But I can't see a way of creating them. Is it possible?

The answer is yes, there is a way to create interfaces using the "ip
address" tool, so that they are recognizable to ifconfig.  You are looking
for the "label" keyword to the "ip address add" command [0].

 : (I know somebody may say "why would I want to" -- it's just for
 : neatness, so that people using 'ifconfig' can still see all the
 : addresses in use.)

I know exactly why an administrator would wish to do this.  Some
administrators, who a) have not joined the 21st century with Linux, or b)
do not commonly use Linux, but rather other UNIX-like operating systems,
may not know about the "ip" utility, but they certainly know about
ifconfig!  So, if only for the humans, this can be helpful.

-Martin

 [0] http://linux-ip.net/html/tools-ip-address.html#ex-tools-ip-address-del

-- 
Martin A. Brown --- SecurePipe, Inc. --- mabrown@securepipe.com

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