Friend, i believe u r trying to do virtual ip on a same NIC.
I suggest u to do these:
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Requirement
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1. One NIC (eth0)
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Question 1
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1. You just answered it yourself, restart the eth0 device
2. If haf more than one eth (say eth0, eth1, eth2), and u wanna clear of eth0, or eth0:0 or eth0:1 only. U can do this:
bash# ifdown eth0;ifup eth0
NOTE: THIS IS ONLY FOR REDHAT/FEDORA CORE ONLY
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Question 2
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Hmm, as mentioned above, what are u trying to do is to create another virtual NIC (with a virtual IP). It's not real, and definitely it's gone after reboot since it's not persistent.
If u want a virtual ip always exist everytime u restart your NIC or reboot or start ur Linux. Do this:
login as: root
root@192.168.0.123's password:
Last login: Tue Jan 24 01:17:00 2006
[root@rh9 root]# cd /etc/sysconfig/network-scripts/
[root@rh9 root]# cp -a ifcfg-eth0 ifcfg-eth0_1
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And your should set the virtual ip like this
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DEVICE=eth0:1
BOOTPROTO=static
BROADCAST=192.168.1.255
IPADDR=192.168.1.123
NETMASK=255.255.255.0
NETWORK=192.168.1.0
ONBOOT=yes
[root@rh9 root]# service network restart
For your information, this is done for Redhat 9, applies to all Redhat Distros including Fedora Core.
For Slackware users, if u do requests for it, u can PM me to do so. I will put it here as well