netmask(1) [debian man page]

NETMASK(1)							   Debian Linux 							NETMASK(1)

NAME

       netmask - a netmask generation and conversion program

SYNOPSIS

       netmask [ options ] spec [ spec ... ]

DESCRIPTION

       This  program  accepts  and  produces a variety of common network address and netmask formats.  Not only can it convert address and netmask
       notations, but it will optimize the masks to generate the smallest list of rules.  This is very handy if you've ever configured a  firewall
       or  router  and	some  nasty  network  administrator  before  you  decided that base 10 numbers were good places to start and end groups of
       machines.

OPTIONS

       -h, --help
	      Print a summary of the options

       -v, --version
	      Print the version number

       -d, --debug
	      Print status/progress information

       -s, --standard
	      Output address/netmask pairs

       -c, --cidr
	      Output CIDR format address lists

       -i, --cisco
	      Output Cisco style address lists

       -r, --range
	      Output ip address ranges

       -x, --hex
	      Output address/netmask pairs in hex

       -o, --octal
	      Output address/netmask pairs in octal

       -b, --binary
	      Output address/netmask pairs in binary

       -n, --nodns
	      Disable DNS lookups for addresses

DEFINITIONS

       A spec is an address specification, it can look like:

       address
	      One address.

       address1:address2
	      All addresses from address1 to address2.

       address1:+address2
	      All addresses from address1 to address1+address2.

       address/mask
	      A group starting at address spanning mask.

       An address is an internet network address, it can look like:

       ftp.gnu.org
	      An internet hostname.

       209.81.8.252
	      A standard dotted quad internet address notation.

       100    A decimal number (100 in this case).

       0100   An octal number preceded by "0" (64 in this case).

       0x100  A hexadecimal number preceded by "0x" (256 in this case).

       A mask is a network mask, it can look like:

       255.255.224.0
	      A dotted quad netmask (netmask will complain if it is not a valid netmask).

       0.0.31.255
	      A Cisco style inverse netmask (with the same checks).

       8      The number of bits set to one from the left (CIDR notation).

       010    The number of bits set to one from the left in octal.

       0x10   The number of bits set to one from the left in hexadecimal.

AUTHOR

       netmask was written by Robert Stone.  Some algorithm design and optimization was provided by Tom Lear.  This manual  page  was  written	by
       Robert Stone.

BUGS

       Let me know if you find any.  This man page is a bit more simplistic than I'd like, but I've forgotten most of the groff I once knew.

SEE ALSO

       ipchains(1), ipfwadm(8), netstat(8), route(8), routed(8), gated(8), tcpd(8)

Debian Project							    15 May 1999 							NETMASK(1)

securenets(4)						     Kernel Interfaces Manual						     securenets(4)

NAME

       securenets - NIS map security file

DESCRIPTION

       The  file  defines  networks  and  hosts  that  can  access the NIS maps on a server.  Each line in the file gives a network mask and a net
       address.  For example:

       The format of the file is as follows:

       o  Lines beginning with the character are treated as comments.

       o  Lines that are not comment lines contain two fields separated by white space.  The first field is a netmask, and the second field  is  a
	  network.

       o  The netmask field can be one of the following:

	      o  255.255.255.255 (IPv4)
	      o  ffff:ffff:ffff:ffff:ffff:ffff:ffff:ffff (IPv6)
	      o  the string indicating that the second field is a specific host to be allowed access.

       The file can have any number of netmask/net pairs.

       When  is  started  on  the  server,  it	checks	for the existence of and reads its contents into memory if it exists.  must be stopped and
       restarted for any changes in to take effect.

       Upon startup, the netmask and the net address are converted to binary format and logical ANDed.	The result must equal the net address (the
       second address) to be legal.

       If  the netmask is 255.255.255.255 (all 1's in binary), any address in the net address argument will match it.  If any field in the netmask
       is 0, the corresponding field in the net address must be 0.  When used in this way, the portion of the addresses given as 0 acts as a  wild
       card.

       When  a	client attempts to bind to the server, checks the client's IP against those given in the file.	Again, the address is converted to
       binary and logical ANDed with the netmask.  The result must equal the net address given in the file.  If the client address does not  match
       any pairs in the file, the binding is refused with the message, "no such map in server's NIS domain".

       The file can be used to limit access to specific hosts or to subnets using the wildcard capability.

       If there are syntax errors in the file, messages are logged to the logging file (default and is not started.

       If a host has multiple interfaces, each interface address must be allowed in the securenets file for that host to have reliable NIS access.

EXAMPLES

       The following examples show entries for the file.

       Either of the following entries provides access only to the host with address 192.33.33.33:

	      or

       The following entry allows access by any host on the 192.33.33 subnet:

       For broader access, such as an entire enterprise, the following entry allows any host whose address begins with "15" to be served:

       Either of the following entries allows access for an individual IPv6 address:

	      or

       The following entry allows access for all IPv6 addresses starting with "fec0":

SEE ALSO

       ypserv(1M).

																     securenets(4)