Linux - NetworkingThis forum is for any issue related to networks or networking.
Routing, network cards, OSI, etc. Anything is fair game.
Welcome to LinuxQuestions.org, a friendly and active Linux Community.
You are currently viewing LQ as a guest. By joining our community you will have the ability to post topics, receive our newsletter, use the advanced search, subscribe to threads and access many other special features. Registration is quick, simple and absolutely free. Join our community today!
Note that registered members see fewer ads, and ContentLink is completely disabled once you log in.
If you have any problems with the registration process or your account login, please contact us. If you need to reset your password, click here.
Having a problem logging in? Please visit this page to clear all LQ-related cookies.
Introduction to Linux - A Hands on Guide
This guide was created as an overview of the Linux Operating System, geared toward new users as an exploration tour and getting started guide, with exercises at the end of each chapter.
For more advanced trainees it can be a desktop reference, and a collection of the base knowledge needed to proceed with system and network administration. This book contains many real life examples derived from the author's experience as a Linux system and network administrator, trainer and consultant. They hope these examples will help you to get a better understanding of the Linux system and that you feel encouraged to try out things on your own.
Click Here to receive this Complete Guide absolutely free.
I am a newbie to Linux and Ubuntu, so please excuse any stupid questions.
The problem that I am having is that after installing Ubuntu, I am not able to access the internet. More specifically, I cannot ping the router and the DHCP is not working.
ping -c 5 192.168.1.1 outputs:
PING 192.168.1.1 (192.168.1.1) 56(84) bytes of data.
From 192.168.1.20 icmp_seq=1 Destination Host Unreachable
The second line is repeated 5 times. By the way, the reason that says "From 192.168.1.20" is because I have assigned the IP adress by executing "sudo ifconfig eth0 192.168.1.20 netmask 255.255.255.0 up". After executing sudo dhclient again, it outputs "connect: Network is unreachable" and ifconfig eth0 does not show an IP adress.
When executing dhclient, this is the output:
Listening on LPF/eth0/00:c0:a8:87:26:7d
Sending on LPF/eth0/00:c0:a8:87:26:7d
Sending on Socket/fallback
DHCPDISCOVER on eth0 to 255.255.255.255 port 67 interval 3 (this line is repeated several times)
No DHCPOFFERS received.
No working leases in persisent databasee - sleeping.
Other relevant information (as gathered from other forums):
But what I posted above is what you are asking for. If I assign a static IP, then pinging the router (192.168.1.1) still doesn't work, because it gives me the "Destination Host Unreachable". That is what the ping I showed was for. Sorry if I did not make this clear.
It could be creating some conflicts. The next step after this is to check the physical wiring and stuff... there's really not much else you can do - clearly the OS is picking up the ethernet card if the interface exists, and if you're able to set parameters like ip address with no problems then there's no software faults as far as I could tell.
Try resting your router (power off, keep it off for a few minutes, turn it back on)
Try using another ethernet patch cord
Try connecting the computer via crossover cable to another system and making them communicate to isolate whether this problem is reproducible with other networks
As I understand, it can access the ethernet card, but not the router, because pinging the router or any other computer on the network results in the Destnation Host Unreachable. (All the other computers are running XP)
The same computer is also running Windows XP, and if I reboot into Windows, the internet works fine, so I don't think this could be a hardware problem.
Resting the router does not seem to help either. I'll try to see whether the same problem is reproductible with either networks though. Thanks for the suggestion.
ok, seems fairly odd, subnet is fine and such, which would be my first point of call.
i've seen various things like icmp packets coming back malformed and such, we can back up to a lower level farily easily though.
firstly, is this host listed in your arp records? it shouldn't be based on the host unreachable message. after pinging it, run "arp -n" to list the known entries. if it's not, let's also look at the initial arping and icmp packets. run "tcpdump -vn arp or icmp" and try a ping. if it's not in the arp cache, you should firstly see the arp broadcast, and then IF the arp is successful, the icmp echo request itself. you'd probably want to totally fluch to arp cache first too.