# USER can be "all", a user name, a group name prefixed with "+", or
# a comma-separated list thereof. In both the DATABASE and USER fields
# you can also write a file name prefixed with "@" to include names from
# a separate file.
#
# CIDR-ADDRESS specifies the set of hosts the record matches.
# It is made up of an IP address and a CIDR mask that is an integer
# (between 0 and 32 (IPv4) or 128 (IPv6) inclusive) that specifies
# the number of significant bits in the mask. Alternatively, you can write
# an IP address and netmask in separate columns to specify the set of hosts.
－－只提到32和128。。。IP+掩码的，是不是不用/32的？？

#
# METHOD can be "trust", "reject", "md5", "crypt", "password",
# "krb5", "ident", or "pam". Note that "password" sends passwords
# in clear text; "md5" is preferred since it sends encrypted passwords.
#
# OPTION is the ident map or the name of the PAM service, depending on METHOD.

怎么样表示一个网段的所有IP？
0.0.0.0 255.255.255.0？
还是
192.168.88.0 255.255.255.0
还是
*.*.*.* 255.255.255.0
还是
::
注释最好有一个形式化语法和多点实例及对应的含义。。。