hosts.allow(4)                      CLIX                      hosts.allow(4)



  NAME

    hosts.allow, hosts.deny - Host access control files

  DESCRIPTION

    The /etc/hosts.allow file contains a list of local network services and
    the remote clients who will be granted acesss to the specified service
    daemons.

    The /etc/hosts.deny file contains a list of local network services and the
    remote clients who will be denied access to the specified service daemons.

    After the log utility is started, whenever a remote connection request for
    connection to any network service listed in the /etc/inetd.conf file is
    received, the tcpd server reads /etc/hosts.allow and /etc/hosts.deny to
    determine access permissions.

    The format of the files is as follows:

    daemon_list : client_list


    The daemon_list parameter can be one or more of the network services
    listed in the /etc/inetd.conf file.

    The client_list parameter is a list of one or more of the following:

    ⊕  Hostname

    ⊕  Internet address

    ⊕  Domain name

    ⊕  Netgroup name

    ⊕  Internet network number

    Domain names should begin with a dot (.).  Internet network numbers (as
    opposed to Internet host numbers) should end with a dot. Netgroup names
    must begin with the at symbol (@).

    List elements should be separated by blanks or commas.  With the
    exeception of netgroup lookups, all access control parameters are case
    sensitive.

    Access will be granted if a daemon/client pair is matched with an entry in
    the /etc/hosts.allow file.

    If there is no match in the /etc/hosts.allow file (or if the
    /etc/hosts.allow file does not exist), the /etc/hosts.deny file is



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  hosts.allow(4)                      CLIX                      hosts.allow(4)



    checked.  Access will be denied if a daemon/client pair is matched with an
    entry in the /etc/hosts.deny file.

    If there is a match in both files, then the /etc/hosts.allow file takes
    precedence.

    If no access control files exist, access control is turned off and all
    requests are allowed.

    The tokens ALL and LOCAL can also be used.  If ALL is specified for the
    daemon_list then access is granted/denied for all network daemon
    processes.  If ALL is specified for the client_list, then all clients are
    granted/denied access.  If LOCAL is specified for the client_list then any
    client string that does not contain a dot (.) is granted/denied access.

  EXAMPLES

    1.  This example restricts all services to hosts within the local domain
        (hostnames that do not contain a dot), in the "b35.psh.com" domain,
        and below the ".abc.com" domain.  The /etc/hosts.allow file would
        appear as follows:

        ALL : LOCAL, b35.psh.com, .abc.com

        The /etc/hosts.deny file would appear as follows:

        ALL : ALL


    2.  This example allows access to all services for hosts within the
        "netdev" netgroup.  The /etc/hosts.allow file would appear as follows:

        ALL : @netdev

        The /etc/hosts.deny file would appear as follows:

        ALL : ALL


    3.  This example denies all services, except ftp, to all clients.  The
        /etc/hosts.allow file would appear as follows:

        ftpd : ALL

        The /etc/hosts.deny file would appear as follows:

        ALL : ALL

  NOTES

    Netgroups are supported on systems running NIS.



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  hosts.allow(4)                      CLIX                      hosts.allow(4)



    If the TCP/IP logging service finds a syntax error in the /etc/hosts.allow
    or /etc/hosts.deny file, the error is logged to the /usr/adm/tcp_log file.
    A file with a syntax error is ignored by tcpd when determining access
    permissions.

    Lines in the file that begin with a number sign (#) are treated as
    comments and are ignored.

  RELATED INFORMATION

    Commands:  tcpd(8), log(8)

    Files:  inetd.conf(4), tcp_log(4)









































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