Is there a better way to add aliases to an interface?

updateleo · 2011-02-21 05:59:53

Hello All,

I need a little help in adding/binding a few thousand IPs to an interface --e.g. from the wiki: 'https://wiki.archlinux.org/index.php/Co … P_aliasing' the process is to edit the rc.conf and add:
eth0="eth0 192.168.0.1 netmask 255.255.255.0 broadcast 192.168.0.255"
eth0_0="eth0:0 192.168.0.2 netmask 255.255.255.0 broadcast 192.168.0.255"
.
.
eth0_1000="eth0:0 192.168.X.X netmask 255.255.255.0 broadcast 192.168.X.255"
INTERFACES=(lo eth0 eth0_0 ... eth0_1000)

but this solution does not seem practical; in addition, if I create more than two aliases and do an 'ifconfig' only the first two show -- e.g.
1- stop /etc/rc.d/network
2- edit /etc/rc.conf
eth0="eth0 192.168.0.1 netmask 255.255.255.0 broadcast 192.168.0.255"
eth0_0="eth0:0 192.168.0.2 netmask 255.255.255.0 broadcast 192.168.0.255"
eth0_1="eth0:0 192.168.0.3 netmask 255.255.255.0 broadcast 192.168.0.255"
eth0_2="eth0:0 192.168.0.4 netmask 255.255.255.0 broadcast 192.168.0.255"
INTERFACES=(lo eth0 eth0_0 eth0_1 eth0_2)
3- start /etc/rc.d/network
4- ifconfig -a
only eth0 and eth0:0 display

would it be an option to add the 'ifconfig' cmd to the rc.local to bind the IPs after boot?

any help will be appreciated
Thanks

cactus · 2011-02-21 07:59:43

With that many ips, I would probably use iproute2 utils (namely ip addr add) instead of ifconfig.
Maybe put some shell scripting in rc.local or create a custom rc.d daemon script to add the ips.

/etc/rc.d/network_holycrap start

Aside: Why in the name of all that is holy would _one machine_ need thousands of IPs!?!?

fukawi2 · 2011-02-21 08:55:22

cactus wrote:

Aside: Why in the name of all that is holy would _one machine_ need thousands of IPs!?!?

I'm curious too, but I have a feeling I'm going to regret knowing...

Something like this in rc.local (or your own init script in /etc/rc.d/) should get you going.... Assuming you're using contiguous addresses.

Requires iproute2

/etc/rc.local

/path/to/add_range.sh 192.168.1.1 192.168.1.254 eth0
/path/to/add_range.sh 192.168.2.1 192.168.2.254 eth0
/path/to/add_range.sh 192.168.3.1 192.168.3.254 eth0

add_range.sh

IPADDR_START=$1
IPADDR_END=$2
DEVICE=$3

ipaddr_prefix=${IPADDR_START%.*}
ipaddr_startnum=${IPADDR_START##*.}
ipaddr_endnum=${IPADDR_END##*.}

if [ "${IPADDR_START%.*}" != "${IPADDR_END%.*}" ]; then
        echo $"error: IPADDR_START and IPADDR_END don't agree" >&2; exit 1
fi

if [ $ipaddr_startnum -gt $ipaddr_endnum ]; then
        echo $"error: IPADDR_START greater than IPADDR_END" >&2; exit 1
fi

ipaddr_num=$ipaddr_startnum
ipaddr_clonenum=$CLONENUM_START

while [ $ipaddr_num -le $ipaddr_endnum ]; do
         IPADDR="$ipaddr_prefix.$ipaddr_num"
         ip a a $IPADDR/24 dev $DEVICE
         let 'ipaddr_num=ipaddr_num+1'
         let 'ipaddr_clonenum=ipaddr_clonenum+1'
done

Credit: CentOS network init script; modified (from initscripts package, licensed under GPLv2)

Last edited by fukawi2 (2011-02-21 08:57:29)

cactus · 2011-02-21 10:00:18

fukawi2 wrote:

cactus wrote:
Aside: Why in the name of all that is holy would _one machine_ need thousands of IPs!?!?
I'm curious too, but I have a feeling I'm going to regret knowing...

haha. yeah.
I fear it will come down to something like "why not just use net.ipv4.ip_nonlocal_bind=1 ?" or "use routing"

Last edited by cactus (2011-02-21 10:00:36)

updateleo · 2011-02-21 15:00:07

First of all, thank you for all your replies and I will try them a bit later and let you know of the result.
The reason for adding the IPs on the arch server is because the box will serve as a VOIP simulator (running individual users with a unique IP) to test a soft switch. So eventually I will need to add the max number of IPs a linux box can hold.

fukawi2 · 2011-02-21 21:57:58

updateleo wrote:

...the max number of IPs a linux box can hold.

Is there a limit other than hardware capabilities?

updateleo · 2011-02-22 03:52:10

SOLVED
fukawi2, cactus thanks for your help; iproute2 and the script was the solution.
there is no limit on the amount of IPs you can add to linux, but I meant the box I was working with, as it has 8G of memory so I can possibly add six thousand IPs before I start seeing performance issues.

Thanks again.

Last edited by updateleo (2011-02-22 03:52:49)

ghen · 2011-02-22 10:46:29

It would be more interesting to generalize this. rc.conf could eg. refer to an external file listing "ip" or "ifconfig" commands to configure the network, like on NetBSD (/etc/ifconfig.<interface>). And refer to /etc/hostname for the hostname.

This way, /etc/rc.conf could be shared between multiple machines serving the same purpose, and differing only in network configuration.

Arch Linux

#1 2011-02-21 05:59:53

Is there a better way to add aliases to an interface?

#2 2011-02-21 07:59:43

Re: Is there a better way to add aliases to an interface?

#3 2011-02-21 08:55:22

Re: Is there a better way to add aliases to an interface?

#4 2011-02-21 10:00:18

Re: Is there a better way to add aliases to an interface?

#5 2011-02-21 15:00:07

Re: Is there a better way to add aliases to an interface?

#6 2011-02-21 21:57:58

Re: Is there a better way to add aliases to an interface?

#7 2011-02-22 03:52:10

Re: Is there a better way to add aliases to an interface?

#8 2011-02-22 10:46:29

Re: Is there a better way to add aliases to an interface?

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