[root@localhost ~]# vim test.txt

2014-08-17
 20140907
 14 03 22



 192.168.1.2
 121.168.2.3

 123-212-2-3

 [root@localhost ~]# grep "[0-9]\{1,3\}[.][0-9]\{1,3\}[.][0-9]\{1,3\}[.][0-9]\{1,3\}" test.txt 
 192.168.1.2
 121.168.2.3

 [root@localhost ~]# grep "[0-9]\{1,3\}\.[0-9]\{1,3\}\.[0-9]\{1,3\}\.[0-9]\{1,3\}" test.txt 
 192.168.1.2
 121.168.2.3