I'm not getting any traction on this question in the Fedora or Newbie forums, so maybe this is the right place to start:

A very strange thing happened to me a couple of nights ago. I'm using Fedora Core 3. I checked up2date and found about five things to download and install, including an update to the kernel (don't remember any of the others). I've always accepted all changes, and I did the same this time. After everything was installed, I restarted the machine and now I can no longer see the WAN. I can see all the other machines on my LAN just fine. I rebooted under the old kernel and it still doesn't work. I rebooted under Win2K and that works fine, so there is no hardware problem.

I can ping any address on my LAN (192.168.1.x) and I get a perfect response. I can open the web pages associated with my router, my wireless access point, and my print server. When I try to ping any internet address, including my router's gateway, I get a "Connect: network is unreachable" message. It was working perfectly immediately before I ran up2date and installed the new packages, and it hasn't worked since.

Of course, I've rebooted numerous times and verified that my firewall is disabled. My router is providing DHCP services for me and assigning an IP address correctly, just as before.

Does anybody have any ideas? What could have happened? I'm seriously considering reinstalling the system today, but I hope it doesn't have to be as drastic as that.

One more thing - I can VNC into the Linux machine from other machines on my network and I can see the Samba server from Windows and OS X machines.

I just can't get Linux to see outside of my LAN!

Any help will be greatly appreciated.

I experienced the same problem recently. I could ssh into my newly updated FC3 2.6.10. I could ping inside my network, but not out. I noticed 2 problems one was that my [B}default route[/B] was gone. So I added it back:

Destination Gateway Genmask Flags MSS Window irtt Iface
default 192.168.1.1 255.255.255.255 UGH 0 0 0 eth0
192.168.1.0 * 255.255.255.0 U 0 0 0 eth0
169.254.0.0 * 255.255.0.0 U 0 0 0 eth0
default 192.168.1.1 0.0.0.0 UG 0 0 0 eth0

Still did not fix the problem, then I noticed that I still had an old static route in my /etc/sysconfig/network-scripts file. (I recently got a new router and never had to make any changes)

***OLD***
DEVICE=eth0
BOOTPROTO=dhcp
ONBOOT=yes
USERCTL=no
PEERDNS=yes
TYPE=Ethernet
IPADDR=192.168.1.10
NETMASK=255.255.255.0
GATEWAY=192.168..1.1
NETWORK=192.168.1.0
BROADCAST=192.168.1.255

I edited my /etc/sysconfig/network-scripts like below:
DEVICE=eth0
BOOTPROTO=dhcp
ONBOOT=yes
TYPE=Ethernet
NETMASK=255.255.255.0
USERCTL=no
PEERDNS=yes
IPV6INIT=no

Then I restarted my network /etc/init.d/network restart and now I can surf and ssh from the updated kernel.
Hope this helps.....