[CentOS] What on Centos is wiping out my eth0 IP address every 5minutes?
Jason Pyeron
jpyeron at pdinc.us
Tue Jul 23 21:49:41 UTC 2013
> -----Original Message-----
> From: Rock
> Sent: Tuesday, July 23, 2013 17:46
>
> QUESTION:
> Why does my Centos 6.4 laptop keep wiping out my eth0 IP address?
Googling
https://www.google.com/search?q=rhel+6+network+configuration&oq=rhel+6+network
https://access.redhat.com/site/documentation/en-US/Red_Hat_Enterprise_Linux/6/ht
ml/Deployment_Guide/ch-Network_Interfaces.html
>
> SUMMARY:
> a) I set the IP address of eth0
> b) Everything works fine for 2 to 5 minutes
> c) Then, that eth0 IP address is (somehow?) wiped out I frustratingly
> repeat that abc process (over and over and over again)
What is the contents of /etc/sysconfig/network-scripts/ifcfg-eth0 ?
>
> BACKGROUND:
> My home network has been working perfectly and there is no problem
> with my home network, nor my wlan0 WiFi access from my Centos laptop
> to that home broadband network.
>
> Inside the house, I never use the wired (eth0) NIC; but, I'm trying to
> set up a wired/wireless connection outside the house and that is where
> I'm running into this problem where Centos (automatically?) constantly
> and repeatedly wipes out the IP address I set on eth0.
>
> I can easily (constantly) change the IP address of the eth0 NIC back
> to what I want it to be; but that IP address only stays set for about
> 2 to 5 minutes; and then it wipes itself out (again & again).
>
> Why? How do I stop this?
> (All I want is for eth0 to *stay* at the IP address I set it to!)
>
> To give you more contextual detail, here's a typical sequence.
>
> SIMPLE BASELINE:
> Wireless NIC (wlan0) is turned off using a hardware switch on the
> outside of the laptop (so that only one NIC is in play).
>
> STARTING POINT: (eth0 has no IP address) $ ifconfig eth0 => eth0 Link
> encap:Ethernet HWaddr A0:BE:C1:D8:E5:F1
> => inet6 addr: fe80::f2de:f1ff:fe38:8591/64 Scope:Link
> => UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
> => RX packets:3139 errors:0 dropped:0 overruns:0 frame:0
> => TX packets:3230 errors:0 dropped:0 overruns:0 carrier:0
> => collisions:0 txqueuelen:1000
> => RX bytes:2403080 (2.2 MiB) TX bytes:547895 (535.0 KiB)
> => Interrupt:20 Memory:f2600000-f2620000
>
> I EASILY CAN SET THE IP ADDRESS of eth0:
> $ sudo ifconfig eth0 192.168.1.100
> $ ifconfig eth0
> => eth0 Link encap:Ethernet HWaddr A0:BE:C1:D8:E5:F1
> => inet addr:192.168.1.100 Bcast:192.168.1.255
> Mask:255.255.255.0
> => inet6 addr: fe80::f2de:f1ff:fe38:8591/64 Scope:Link
> => UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
> => etc.
>
> At this point, I can now connect a wire from the RJ45 port of the
> laptop, to the device (which happens to be a radio set to
> 192.168.1.20):
>
> $ ping 192.168.1.20
> => PING 192.168.1.20 (192.168.1.20) 56(84) bytes of data.
> => 64 bytes from 192.168.1.20: icmp_seq=1 ttl=64 time=1.38 ms => 64
> bytes from 192.168.1.20: icmp_seq=2 ttl=64 time=0.339 ms => 64 bytes
> from 192.168.1.20: icmp_seq=3 ttl=64
> time=0.255 ms ^C => --- 192.168.1.20 ping statistics --- => 3 packets
> transmitted, 3 received, 0% packet loss, time 2954ms => rtt
> min/avg/max/mdev = 0.255/0.660/1.388/0.516 ms
>
> I can even easily connect via port 80 (using Firefox on the
> laptop) to this device, e.g., $ firefox http://192.168.1.20
>
> In fact, time and time (and time) again, everything works just fine,
> for about 2 to 5 minutes, until, invariably, I lose all connectivity!
>
> What seems to happen is that CentOS wipes out my IP address that I had
> set for eth0. So, I lose all connectivity.
>
> $ ifconfig eth0
> => eth0 Link encap:Ethernet HWaddr A0:BE:C1:D8:E5:F1
> => inet6 addr: fe80::f2de:f1ff:fe38:8591/64 Scope:Link
> => UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
>
> I can repeat the process, and everything works again, for about 2 to
> 5 minutes. Then I lose my eth0 IP address again.
>
> WHAT I WANT:
> When I set eth0 to an IP address, I want eth0 to *stay* at that IP
> address!
>
> My question:
> Q: Why does setting an eth0 IP address only last about 5 minutes on
> Centos?
> What am I doing wrong?
> What can I do to *keep* the IP address on eth0 that I set for eth0?
>
>
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> CentOS at centos.org
> http://lists.centos.org/mailman/listinfo/centos
>
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