I can easily grant access to one IP using this code:
$ mysql -u root -p
Enter password:
mysql> use mysql
mysql> GRANT ALL ON *.* to root@\'192.
Just a note of a peculiarity I faced:
Consider:
db server: 192.168.0.101
web server: 192.168.0.102
If you have a user defined in mysql.user as 'user'@'192.168.0.102' with password1 and another 'user'@'192.168.0.%' with password2,
then,
if you try to connect to the db server from the web server as 'user' with password2,
it will result in an 'Access denied' error because the single IP 'user'@'192.168.0.102' authentication is used over the wildcard 'user'@'192.168.0.%' authentication.