[root@localhost ~]# more qq.txt
11.1.1.1
232.232.11.1
222.2.2.2
122.222.222.222
333.333.33.11
255.555.555.55

1.0.0.1
1.1.1.1111
255.255.255.254
255.255.255.255
255.255.255.255
255.255.255.255.0
2111.111.111.11
254.255.255.255
254.15.11.255
0.0.0.1
0.11.111.111

66.244.13.2
99.100.199.199

1.1.1.1
255.255.255.255

[root@localhost ~]# grep -P '^(([1-9]|([1-9]\d)|(1\d\d)|(2([0-4]\d|5[0-5])))\.)((\d|([1-9]\d)|(1\d\d)|(2([0-4]\d|5[0-5])))\.)((\d|([1-9]\d)|(1\d\d)|(2([0-4]\d|5[0-5])))\.)((\d|([1-9]\d)|(1\d\d)|(2([0-4]\d|5[0-5]))))$' qq.txt
11.1.1.1
232.232.11.1
222.2.2.2
122.222.222.222
1.0.0.1
255.255.255.254
255.255.255.255
255.255.255.255
254.255.255.255
254.15.11.255
66.244.13.2
99.100.199.199
1.1.1.1
255.255.255.255