ping socket: Permission denied

I am root.
ping 127.0.0.1 and return error;

root@sam-PC:~# ping 127.0.0.1 
socket: Permission denied

root@sam-PC:~# ifconfig
eth0      Link encap:Ethernet  HWaddr 00:00:ff:ff:00:00  
          inet addr:192.168.100.104  Bcast:192.168.100.255  Mask:255.255.255.0
          inet6 addr: fe80::200:ffff:feff:0/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:36 errors:0 dropped:0 overruns:0 frame:0
          TX packets:7 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000 
          RX bytes:2220 (2.2 KB)  TX bytes:524 (524.0 B)

lo        Link encap:Local Loopback  
          inet addr:127.0.0.1  Mask:255.0.0.0
          inet6 addr: ::1/128 Scope:Host
          UP LOOPBACK RUNNING  MTU:16436  Metric:1
          RX packets:40 errors:0 dropped:0 overruns:0 frame:0
          TX packets:40 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0 
          RX bytes:3160 (3.1 KB)  TX bytes:3160 (3.1 KB)



root@sam-PC:~# ping 192.168.100.100
socket: Permission denied

who knows why?

For this problem, we should add the following lines to /etc/group:

inet:x:3003:root
net_raw:x:3004:root