Red Hat ENTERPRISE LINUX 4.5.0 Reference Manual page 337

• — Matches any host where the hostname or host address are unknown or where
UNKNOWN
the user is unknown.
• — Matches any host where the hostname does not match the host address.
PARANOID
Caution
The
KNOWN
disruption in name resolution may prevent legitimate users from gaining access
to a service.
2.1.2. Patterns
Patterns can be used in the client list field of access rules to more precisely specify groups of
client hosts.
The following is a list of the most common accepted patterns for a client list entry:
• Hostname beginning with a period (
matches all hosts sharing the listed components of the name. The following example applies
to any host within the
ALL : .example.com
• IP address ending with a period (
all hosts sharing the initial numeric groups of an IP address. The following example applies to
any host within the
192.168.x.x
ALL : 192.168.
• IP address/netmask pair — Netmask expressions can also be used as a pattern to control
access to a particular group of IP addresses. The following example applies to any host with
an address range of
ALL : 192.168.0.0/255.255.254.0
Important
When working in the IPv4 address space, the address/prefix length (prefixlen)
, , and
UNKNOWN PARANOID
) — Placing a period at the beginning of a hostname
.
domain:
example.com
) — Placing a period at the end of an IP address matches
.
network:
through
192.168.0.0
wildcards should be used with care as a
:
192.168.1.255
Formatting Access Rules
313