Hosts.allow / deny

[D u n c a n]

Hie all,
Fedora Core 2 ,squirrelmail ,sendmail
how do i securely insure my hosts.alllow and deny is correctly
configured.At the moment its configured as such:

hosts.allow
          ALLOW : imapd :  127.0.0.1
          ALLOW : sshd  : 10.10.10.2
          ALLOW : smtp : 10.10.10.3
hosts.deny
          ALL : ALL
          
i just want to allow access to imapd,sshd and my smarthost
Will this kill the DNS service etc .Suggestions welcome
 .Firewall is too costly



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Duncan Rack