Multiple IPs on single interface

[Mike Burger]

FWIW, it might be a better alternative, instead of the ethX:Y setups, via 
virtual interfaces, to simply alias the IPs using the "ip addr add" 
commands.  You simply add lines like the following into your 
/etc/init.d/rc.local file:

ip addr add xxx.xxx.xxx.xx1 dev eth0
ip addr add xxx.xxx.xxx.xx2 dev eth0

There are a number of fairly good reasons to go with this type of setup, 
rather than virtual ethX:Y interfaces:

1) You don't have to keep track of what interfaces are set up.
2) You don't have to maintain multiple configuration files for all of 
   those virtual interfaces.
3) I've found, in the past, that iptables doesn't like working with the 
   virtual interfaces all that much.  Working with standard interface 
   devices, like eth0, eth1, and then just the IPs, has seemed to work 
   much better for me.

On Tue, 15 Feb 2005, Smith, Albert wrote:

> 256 is the maxium amount of ip address that can be bound to a single nic
> 
> Albert Smith
> Sr. Unix Systems Administrator
> Genex Services
> 440 E. Swedesford Rd.
> Wayne, PA 19087
> albert.smith at genexservices.com
> (610) 964-5154
> 
> 
> 
> -----Original Message-----
> From: redhat-list-bounces at redhat.com on behalf of Jason Williard
> Sent: Tue 2/15/2005 1:17 AM
> To: 'General Red Hat Linux discussion list'
> Subject: RE: Multiple IPs on single interface
>  
> That worked.  Thank you very much.  Do you know if there is a max limit on
> how many IP's can be attached to a single interface?  Also, is there a way
> to add an entire subnet without creating 1 file for each IP?
> 
> ---
> Thank You,
> Jason Williard
> PCSafe, Inc.
>  
>  
> 
> -----Original Message-----
> From: redhat-list-bounces at redhat.com [mailto:redhat-list-bounces at redhat.com]
> On Behalf Of IAK Tanoli
> Sent: Monday, February 14, 2005 10:08 PM
> To: General Red Hat Linux discussion list
> Subject: Re: Multiple IPs on single interface
> 
> 
> Modify the file as following. 
> 
> DEVICE=eth0:1
> ONBOOT=yes
> BOOTPROTO=static
> IPADDR=xxx.xxx.xxx.xxx
> NETMASK=255.255.254.0
> GATEWAY=xxx.xxx.xxx.xxx
> HWADDR=00:00:00:00:00:00
> 
> --- Jason Williard <jason at pcsafe.com> wrote:
> 
> > Hello,
> > 
> > I have a box with Red Hat Enterprise Linux ES
> > release 3 installed on it.
> > Today, I acquired 2 additional IP addresses for it. 
> > I can add the IP
> > addresses using the following commands, but they are
> > not permanent.
> > 
> > # ifconfig eth0 add xxx.xxx.xxx.xxx netmask
> > 255.255.254.0
> > # ifconfig eth0:0 add xxx.xxx.xxx.xxx netmask
> > 255.255.254.0
> > 
> > As this was not making it permanent, I created 2
> > files (ifcfg-eth0:0 &
> > ifcfg-eth0:0:1) inside the
> > /etc/sysconfig/network-scripts/ directory.  The
> > first file works and interface eth0:0 comes up at
> > startup.  However, the
> > second interface stays down.  Below is the content
> > of the two files:
> > 
> > ifcfg-eth0:0
> > ---
> > DEVICE=eth0:0
> > ONBOOT=yes
> > BOOTPROTO=static
> > IPADDR=xxx.xxx.xxx.xxx
> > NETMASK=255.255.254.0
> > GATEWAY=xxx.xxx.xxx.xxx
> > HWADDR=00:00:00:00:00:00
> > ---
> > 
> > ifcfg-eth0:0:1
> > ---
> > DEVICE=eth0:0:1
> > ONBOOT=yes
> > BOOTPROTO=static
> > IPADDR=xxx.xxx.xxx.xxx
> > NETMASK=255.255.254.0
> > GATEWAY=xxx.xxx.xxx.xxx
> > HWADDR=00:00:00:00:00:00
> > ---
> > 
> > 
> > ---
> > Thank You,
> > Jason Williard
> > PCSafe, Inc.
> >  
> >  
> > 
> > 
> > 
> > 
> > -- 
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> > unsubscribe
> >
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> > https://www.redhat.com/mailman/listinfo/redhat-list
> > 
> 
> 
> =====
> --
> 
> ________________
> Imtiaz Ahmed Khan
> Sr. System Consultant
> ANTS Consultiing
> 
> 
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-- 
Mike Burger
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