CentOS

I installed CentOS 6.5 as guest with VituralBox on Windows 7. Set NAT in VM for network setting. then modify scripts for eth0 in Linux:

NETMASK=255.255.255.0
IPADDR=192.168.0.21
GETWAY=192.168.0.1

when Linux reboot, there are a few thing happening:
1. the IP is 10.0.2.15, not 192.168.0.21
2. I can ping Windows 7 host(IP is 192.168.0.12) from linux
3. but I can't ping 10.0.2.15 from Windows 7 host.
4. I can ping www.google.com from linux to verify internet connection go through.

Question:
1. Why can't ping 10.0.2.12 from Windows 7? because of firewall? if yes, how to turn it off?
I want to linux and windows in same segment with IP like 192.168.0.21, how to do it?

Do you have to use NAT? If you can use the "bridged" network, things will be easier. If you must use NAT, you may want to read this chapter for help.

thanks. turn to bridge. then host and guest in same segment and can communicate each other, but can't ping www.google.com from CentOS any more. It is okay from host.

Can you ping if you use IP?

no. This is result if I use www.google.com IP(74.125.225.18):

[root@cent ~]# ping 74.125.225.18
connect: Network is unreachable
[root@cent ~]# ping 192.168.0.16
PING 192.168.0.16 (192.168.0.16) 56(84) bytes of data.
64 bytes from 192.168.0.16: icmp_seq=1 ttl=128 time=0.469 ms
64 bytes from 192.168.0.16: icmp_seq=2 ttl=128 time=0.498 ms

192.168.0.16 is windows 7 host.

this is ping from host windows 7 to guest CentOS:

C:\Users\KENT>ping 192.168.0.21
Pinging 192.168.0.21 with 32 bytes of data:
Reply from 192.168.0.21: bytes=32 time<1ms TTL=64
Reply from 192.168.0.21: bytes=32 time<1ms TTL=64
Reply from 192.168.0.21: bytes=32 time<1ms TTL=64
Reply from 192.168.0.21: bytes=32 time<1ms TTL=64

192.168.0.21 is for guest CentOS.