[Mageia-discuss] Temporarily changing IP address

[Anne Wilson]

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On 22/05/12 16:59, AL13N wrote:
>> On 22/05/12 15:08, AL13N wrote:
>>>>>> No :-(  No difference, even though I restarted the
>>>>>> network service,
>>>> 
>>>> Lets start from scratch.
>>>> 
>>>> But first, can you tell me the ip address of the NAS and
>>>> your laptop's IP address for eth0.
>>>> 
>>>> After making note of these, put the laptop back to it's
>>>> original config. (i.e. remove the manually created interface)
>>>> and set wlan0 not to come up on reboot.  Then restart so you
>>>> only have an ip address on eth0.
>>>> 
>>>> Then send me the info.
>>>> 
>>>> Doug
>>> 
>>> in fact, if we want it to be even simpler, you could add the
>>> ip address without a alias interface wit iproute2
>>> 
>>> []# ip addr show eth0
>> 
>> # ip addr show eth0 2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP>
>> mtu 1500 qdisc pfifo_fast state UP qlen 1000 link/ether
>> 1c:75:08:28:bd:e4 brd ff:ff:ff:ff:ff:ff inet 169.254.100.1/24 brd
>> 169.254.100.255 scope global eth0 inet6
>> fe80::1e75:8ff:fe28:bde4/64 scope link valid_lft forever
>> preferred_lft forever
>> 
>>> []# ip addr add www.xxx.yyy.zzz/netmask dev eth0
>> 
>> # ip addr add www.192.168.0.20/255.255.255.0 dev eth0 Error: an
>> inet prefix is expected rather than 
>> "www.192.168.0.20/255.255.255.0".
>> 
>> Not sure what it is expecting.
> 
> hum, i meant the socalled CIDR notation: 4 parts of ip address
> followed by a subnet mask,
> 
> in your case, i'd do:
> 
> []# ip addr add 192.168.0.20/24 dev eth0
> 
Meanwhile, I played with alternatives, knowing that it must be
something close to what I'd already tried.  So,

# ip addr add 192.168.0.20/255.255.255.0 dev eth0
# ip addr show eth0
2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast
state UP qlen 1000
    link/ether 1c:75:08:28:bd:e4 brd ff:ff:ff:ff:ff:ff
    inet 169.254.100.1/24 brd 169.254.100.255 scope global eth0
    inet 192.168.0.20/24 scope global eth0
    inet6 fe80::1e75:8ff:fe28:bde4/64 scope link
       valid_lft forever preferred_lft forever

So now it appears to have two addresses, preferring the wrong one.

> then if you do
> 
> []# ip addr show eth0
> 
> again, you'd see it was there, as well as the extra route for that
> range:
> 
> []# ip route
> 
# ip route
default via 192.168.0.1 dev eth1  proto static
default via 169.254.100.100 dev eth0  metric 10
default via 192.168.0.1 dev eth1  metric 10
169.254.100.0/24 dev eth0  proto kernel  scope link  src 169.254.100.1
 metric 10
192.168.0.0/24 dev eth1  proto kernel  scope link  src 192.168.0.101
192.168.0.0/24 dev eth0  proto kernel  scope link  src 192.168.0.20
> 
ifconfig
eth0      Link encap:Ethernet  HWaddr 1C:75:08:28:BD:E4
          inet addr:169.254.100.1  Bcast:169.254.100.255
Mask:255.255.255.0

>> 
>> Shorewall and iptables are currently stopped.
> 
> Be careful of this, in your case, it might not matter, but
> shorewall stop has policy DROP, (i think), allthough iptables
> should have policy ACCEPT.
> 
> so, you'd have to stop shorewall first, then stop iptables.

That's the order I did it.
> 
> personally, i'd rather not stop the firewall, due to security
> reasons though. but since with this solution, you don't have any
> extra interface, even just restarting it would be fine.
> 
Once I have a connection I'll restart them.

> if you want to debug even further:
> 
> []# tcpdump -n -i eth0 host <nas_ip>
> 
Where does that write to?  A log file?

> and try to connect and then you can see what sourceip and destip
> are set and if a reply is coming back.
> 
At the end of this, though, I can ping both the NAS on 192.168.0.200
and other LAN connections.

Last question, then, is whether this is a permanent change?

Anne

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