13 replies to this topic

[Vaielab]

Hello,

Today I started my computer who run under ubuntu 11.04 and I didn't have network anymore.
I could not ping the router (192.168.0.1) but everyone else was ok.

On my computer I have some virtualbox installed, and if I start them, I could go on the internet without any problem with them.
Since my last reboot, I didn't change any config on my computer, and I am the only one with the password for the router, so I will be surprise if any config had changed.

Here my ifconfig -a:

eth0      Link encap:Ethernet  HWaddr e0:69:95:78:0e:ab  

          inet addr:192.168.0.101  Bcast:192.168.0.255  Mask:255.255.255.0

          inet6 addr: fe80::e269:95ff:fe78:eab/64 Scope:Link

          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1

          RX packets:14577 errors:0 dropped:0 overruns:0 frame:0

          TX packets:8497 errors:0 dropped:0 overruns:0 carrier:0

          collisions:0 txqueuelen:1000 

          RX bytes:17540278 (17.5 MB)  TX bytes:899519 (899.5 KB)

          Interrupt:20 Memory:fe700000-fe720000 


lo        Link encap:Local Loopback  

          inet addr:127.0.0.1  Mask:255.0.0.0

          inet6 addr: ::1/128 Scope:Host

          UP LOOPBACK RUNNING  MTU:16436  Metric:1

          RX packets:16 errors:0 dropped:0 overruns:0 frame:0

          TX packets:16 errors:0 dropped:0 overruns:0 carrier:0

          collisions:0 txqueuelen:0 

          RX bytes:960 (960.0 B)  TX bytes:960 (960.0 B)


vboxnet0  Link encap:Ethernet  HWaddr 0a:00:27:00:00:00  

          BROADCAST MULTICAST  MTU:1500  Metric:1

          RX packets:0 errors:0 dropped:0 overruns:0 frame:0

          TX packets:0 errors:0 dropped:0 overruns:0 carrier:0

          collisions:0 txqueuelen:1000 

          RX bytes:0 (0.0 B)  TX bytes:0 (0.0 B)

My /etc/network/interfaces

auto lo

iface lo inet loopback


auto eth0

iface eth0 inet dhcp

I tried to remove the 2 last line, but didn't change anything

And my /etc/hosts

127.0.0.1	             localhost

127.0.0.2 	localhost

127.0.0.3	             localhost



# The following lines are desirable for IPv6 capable hosts

::1     ip6-localhost ip6-loopback

fe00::0 ip6-localnet

ff00::0 ip6-mcastprefix

ff02::1 ip6-allnodes

ff02::2 ip6-allrouters

Of course, I tried to reboot my computer, reboot the router, disconnect the router, or reboot my network (both with /etc/init.d/networking restart and ifconfig eth0 down than up)

But absolutly nothing work... I cannot even ping my router
But everything work in my virtualbox machines

Anyone have an idea?!

[WingedPanther]

Your ifconfig indicates you DO have an IP being retrieved from DHCP.
Questions:
1) Does anyone else end up with the same IP address as you?
2) Can you ping google? (one of my favorite tests)
3) Is it possible that your router is just not listening for pings?

[Vaielab]

That the weird thing, I have a ip
No one can have the same ip as me since my ip is reserved on the router (their only 2 ip reserved, mine and the server)
I tried to ping google.ca, google.com and digg.com but nothing, I can't even find the ip address of the domains.
And my router respond to the ping from my virtual machine.

A little update, just by magic, everything resolve itself, and everything work again.
I did not change anything, it simply start to ping again (I hate this)
And since it's my work computer, I prefer to know how to resolve this, because I would hate that the network crash randomly every morning and losing 1h of my time each day.

[WingedPanther]

Unfortunately, if someone is using a static IP instead of DHCP, they could have the same IP as you. Do you have a wireless network that someone could be logging in to?

[Vaielab]

The whole building is connected for the wireless... is there a way to detect if someone is already on my ip?

[haltox]

If you can connect with an other ip, you could ping your ip.

[WingedPanther]

Vaielab said:

The whole building is connected for the wireless... is there a way to detect if someone is already on my ip?

I think you can check on your router.

[Vaielab]

I'll do so, thank you
And do you know any way to protect your ip for nobody use them.

I work in a (not sure how to say it in english) care home for old people, and some of them have computer, and when family come to visit them, they can bring their laptop, and we are all on the same network, so we have absolutly no control over this
With more than 100 resident, plus their family, plus our computers, we really need a way to limit this, lucky for us not a lot of resident have computer

[haltox]

You might be able to reserve the ip for a mac address on the router.

[WingedPanther]

You can control how your router hands out IP addresses, but you can't easily stop people from doing "bad things" ™ when they connect. Having their computer set to use a static IP is something you simply can't block. I've seen the damage that happens when people do that (I saw somebody log in using the static IP of the DHCP server, once). They're circumventing all your configurations when they do that.

[Vaielab]

Well that a bummed :(
I'll tell my boss that we need 2 seperated network, he won't like that :P

Thank you

[WingedPanther]

If you're using a wireless router, you can set it to hand out addresses on a different subnet, and block anything that tries to come through on the "wrong" subnet. Also, a lot of routers let you create Mac address filters, which could simply block "bad" behavior IP traffic.