Linux uses a resolver library to obtain the IP address corresponding to a host name. The /etc/host.conf file specifies how names are resolved. The entries in the etc/host.conf
file tell the resolver library what services to use, and in what order, to resolve names. Edit the host.conf file vi /etc/host.conf and add the following lines:
# Lookup names via DNS first then fall back to /etc/hosts.
order bind,hosts
# We have machines with multiple IP addresses.
multi on
# Check for IP address spoofing.
nospoof on
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The order option indicates the order of services. The sample entry specifies that the resolver library should first consult the name server to resolve a name and then check the /etc/hosts file. It is
recommended to set the resolver library to first check the name server, bind and then the hosts file (hosts) for better performance and security on all your servers. Of course you must have the DNS/BIND software installed
or this configuration will not work.
The multi option determines whether a host in the /etc/hosts file can have multiple IP addresses i.e.multiple interface ethN. Hosts that have more than one IP
address are said to be multiomed, because the presence of multiple IP addresses implies that host has several network interfaces. As an example, a Gateway Server will always have multiple IP address and must have this
option set to ON.
The nospoof option indicates to take care of not permitting spoofing on this machine. IP-Spoofing is a security exploit that works by tricking computers in a trust relationship that you are someone that you really
aren't. In this type of attack, a machine is set up to look like a legitimate server and then issue connections and other types of network activities to legitimate end systems, other servers or large data repository
systems. This option must be set ON for all types of servers.
