netgroup(4)															       netgroup(4)

NAME

       netgroup - list of network groups

SYNOPSIS

       /etc/netgroup

       A  netgroup  defines  a	network-wide group of hosts and users. Use a netgroup to restrict access to shared NFS filesystems and to restrict
       remote login and shell access.

       Network groups are stored in a network information services, such as LDAP, NIS, or NIS+, not in a local file.

       This manual page describes the format for a file that is used to supply input to a program such as ldapaddent(1M) for LDAP, makedbm(1M) for
       NIS, or nisaddent(1M) for NIS+.	These programs build maps or tables used by their corresponding network information services.

       Each line of the file defines the name and membership of a network group. The line should have the format:

       groupname     member...

       The items on a line can be separated by a combination of one or more spaces or tabs.

       The  groupname  is  the	name of the group being defined. This is followed by a list of members of the group. Each member is either another
       group name, all of whose members are to be included in the group being defined, or a triple of the form:

       (hostname,username,domainname)

       In each triple, any of the three fields hostname, username, and domainname, can be empty. An empty field signifies a wildcard that  matches
       any value in that field. Thus:

       everything (,,this.domain)

       defines a group named "everything" for the domain "this.domain" to which every host and user belongs.

       The  domainname	field refers to the domain in which the triple is valid, not the domain containing the host or user. In fact, applications
       using netgroup generally do not check the domainname. Therefore, using

       (,,domain)

       is equivalent to

       (,,)

       You can also use netgroups to  control  NFS  mount  access  (see  share_nfs(1M))  and  to  control  remote  login  and  shell  access  (see
       hosts.equiv(4)). You can also use them to control local login access (see passwd(4), shadow(4), and compat in nsswitch.conf(4)).

       When  used  for these purposes, a host is considered a member of a netgroup if the netgroup contains any triple in which the hostname field
       matches the name of the host requesting access and the domainname field matches the domain of the host controlling access.

       Similarly, a user is considered a member of a netgroup if the netgroup contains any triple in which the username field matches the name	of
       the user requesting access and the domainname field matches the domain of the host controlling access.

       Note  that when netgroups are used to control NFS mount access, access is granted depending only on whether the requesting host is a member
       of the netgroup. Remote login and shell access can be controlled both on the basis of host and user membership in separate netgroups.

       /etc/netgroup	       Used by a network information service's utility to construct a map or table that contains netgroup information. For
			       example, ldapaddent(1M) uses /etc/netgroup to construct an LDAP container.

       Note  that  the	netgroup information must always be stored in a network information service, such as LDAP, NIS, or NIS+. The local file is
       only used to construct a map or table for the network information service. It is never consulted directly.

       nis+(1), ldapaddent(1M), makedbm(1M), nisaddent(1M), share_nfs(1M), innetgr(3C),  hosts(4),  hosts.equiv(4),  nsswitch.conf(4),	passwd(4),
       shadow(4)

       netgroup requires a network information service such as LDAP, NIS, or NIS+.

       Applications may make general membership tests using the innetgr() function. See innetgr(3C).

       Because the "-" character will not match any specific username or hostname, it is commonly used as a placeholder that will match only wild-
       carded membership queries. So, for example:

       onlyhosts (host1,-,our.domain) (host2,-,our.domain)
       onlyusers (-,john,our.domain) (-,linda,our.domain)

       effectively define netgroups containing only hosts and only users, respectively. Any other string that is guaranteed  not  to  be  a  legal
       username or hostname will also suffice for this purpose.

       Use of placeholders will improve search performance.

       When  a	machine  with  multiple  interfaces  and  multiple names is defined as a member of a netgroup, one must list all of the names. See
       hosts(4). A manageable way to do this is to define a netgroup containing all of the machine names. For example, for a host  "gateway"  that
       has names "gateway-subnet1" and "gateway-subnet2" one may define the netgroup:

       gateway (gateway-subnet1,,our.domain) (gateway-subnet2,,our.domain)

       and use this netgroup "gateway" whenever the host is to be included in another netgroup.

								    22 Jul 2004 						       netgroup(4)