add a default route in Linux

Sometimes, even after cmd "dhclient eth0", the machine still cannot ping outside machines.

Then, I use cmd "route" to check the current route, and get sth like this:

Kernel IP routing table
Destination Gateway Genmask Flags Metric Ref Use Iface
192.168.1.0 * 255.255.255.0 U 0 0 0 ra0

So there is no default gatway. Next I use the following command to add a default route:

"route add default gw 192.168.2.1 eth0"
(The IP of the gateway could be the current IP address and change the last number to 1.)

Ref:
http://www.cyberciti.biz/faq/linux-setup-default-gateway-with-route-command/

Linux Virtual Network Interfaces

http://ar.linux.it/docs/vinter/vinter.html

Ubuntu network restart

sudo /etc/init.d/networking restart

Linux: Check Network Connection Command

http://www.cyberciti.biz/faq/check-network-connection-linux/

Linux Tuning
http://fasterdata.es.net/fasterdata/host-tuning/linux/

Some links about network terms

http://en.wikipedia.org/wiki/Network_switch#Layer_3 http://en.wikipedia.org/wiki/LAN_switching http://en.wikipedia.org/wiki/Router http://www.wisc-online.com/objects/ViewObject.aspx?ID=CIS6508 http://www.eventhelix.com/realtimemantra/networking/ip_routing.htm

LInux Neighboring Subsystem

http://blog.csdn.net/rstevens/archive/2007/04/10/1559372.aspx

http://lxr.linux.no/#linux+v2.6.18/net/core/neighbour.c#L817

Linux Tune Network Stack

http://www.cyberciti.biz/faq/linux-tcp-tuning/

Writing network device driver for Linux

http://linuxgazette.net/156/jangir.html

Rtl8139:

http://www.linuxforum.net/forum/showflat.php?Cat=&Board=driver&Number=635688&fpart=1&PHPSESSID=

http://linux.chinaunix.net/bbs/viewthread.php?tid=1095257&extra=&page=1

PCI:

http://www.linuxforum.net/forum/showthreaded.php?Cat=&Board=linuxK&Number=635418&page=&view=&sb=&o=