Can't ping Ubuntu laptop from my LAN

My laptop has Ubuntu 10.10 and is connected to my router with full internet access, yet I can't ping it from other computers on my LAN. I tried the following:

• I can successfully ping those other computers from my Ubuntu laptop, so I didn't accidentally connect to someone else's network.
• I can successfully ping my Ubuntu laptop from itself, though I don't know if that means anything.
• I haven't messed with iptables at all, so it currently doesn't have any rules set that would cause it to reject anything.
• I made a DHCP reservation for my laptop's MAC address in my router to make sure I was always using the correct IP address.

Please note that I am using a "command line only" install of Ubuntu, so I can't use any GUI network config tools. The reason I want to ping it is because I am trying to run an NFS server on the laptop, yet despite correctly setting it up I cannot access the NFS volume on another computer because it isn't even visible on the network right now.

2 Answers

You don't mention whether or not you attempted to ping via hostname or ip address. If by hostname, WINS is not a standard part of Linux (esp a basic install), so most consumer routers and Windows boxes won't be able to connect via hostname. Your router may have a method of manually setting hostnames to a specific MAC or IP address, which could solve the problem. If you have all Linux boxes and are having the problem, try defining the names in /etc/hosts. Finally, try installing WINS if that's the route you like (part of SAMBA):

Not a solution, but a diagnostic tool: try to reach your computer via TCP to rule out the case that something funky is going on with ICMP packets. On the receiving host run

nc -l 8090

while on the other, run

echo hi | nc ip.of.computer 8090

Of course you need to replace of.of.computer with the computer's ip address such as 192.168.0.101. If all goes well, you should see "hi" in the output of the computer you're trying to reach. If not, there is something wrong with your routing or a firewall is blocking incoming packets.