tcp_wrappers_7.6/README.NIS - nest-learning-thermostat/5.1/tcp_wrappers - Git at Google

 @(#) README.NIS 1.2 96/02/11 17:24:52

 > Problem: I have several [machines] with multiple IP addresses, and
 > when they try to connect to a daemon with tcp wrapper, they are often
 > rejected.  I assume this is due to the -DPARANOID option, and depends
 > on which IP address is returned first from the nameserver for a given
 > name.   This behavior seems to be random, may depend on ordering in
 > the YP host map?

 [Note: the situation described below no longer exists. Presently, my
 internet gateway uses the same IP address on all interfaces.  To avoid
 confusion I have removed the old name wzv-gw.win.tue.nl from the DNS. I
 have kept the discussion below for educational reasons].

 NIS was not designed to handle multi-homed hosts.  With NIS, each
 address should have its own hostname. For example, wzv-gw is my
 gateway. It has two interfaces: one connected to the local ethernet,
 the other to a serial link. In the NIS it is registered as:

         131.155.210.23  wzv-gw-ether
         131.155.12.78   wzv-gw-slip

 In principle, wzv-gw could be the official name of one of these
 interfaces, or it could be an alias for both.

 The DNS was designed to handle multi-homed hosts. In the DNS my gateway
 is registered in zone win.tue.nl, with one name that has two A records:

         wzv-gw  IN      A       131.155.210.23
                 IN      A       131.155.12.78

 And of course there are PTR records in zones 210.155.131.in-addr.arpa
 and 12.155.131.in-addr.arpa that point to wzv-gw.win.tue.nl.

 This setup does not cause any problems. You can test your name service
 with the two programs below. This is what they say on a local NIS client
 (both client and server running SunOS 4.1.3_U1):

         % gethostbyname wzv-gw
         Hostname:       wzv-gw.win.tue.nl
         Aliases:
         Addresses:      131.155.210.23 131.155.12.78

         % gethostbyaddr 131.155.210.23
         Hostname:       wzv-gw-ether
         Aliases:
         Addresses:      131.155.210.23

         % gethostbyaddr 131.155.12.78
         Hostname:       wzv-gw-slip
         Aliases:
         Addresses:      131.155.12.78

 Things seem less confusing when seen by a NIS client in a different
 domain (both client and server running SunOS 4.1.3_U1):

         % gethostbyname wzv-gw.win.tue.nl
         Hostname:       wzv-gw.win.tue.nl
         Aliases:
         Addresses:      131.155.210.23 131.155.12.78

         % gethostbyaddr 131.155.210.23
         Hostname:       wzv-gw.win.tue.nl
         Aliases:
         Addresses:      131.155.12.78 131.155.210.23

         % gethostbyaddr 131.155.12.78
         Hostname:       wzv-gw.win.tue.nl
         Aliases:
         Addresses:      131.155.210.23 131.155.12.78

 Alas, Solaris 2.4 still has problems. This is what I get on a Solaris
 2.4 NIS client, with a SunOS 4.1.3_U1 NIS server:

 	% gethostbyname wzv-gw.win.tue.nl
 	Hostname:       wzv-gw.win.tue.nl
 	Aliases:        131.155.210.23 wzv-gw.win.tue.nl
 	Addresses:      131.155.12.78

 The tcpd source comes with a workaround for this problem. The
 workaround is ugly and is not part of the programs attached below.


 #! /bin/sh
 # This is a shell archive.  Remove anything before this line, then unpack
 # it by saving it into a file and typing "sh file".  To overwrite existing
 # files, type "sh file -c".  You can also feed this as standard input via
 # unshar, or by typing "sh <file", e.g..  If this archive is complete, you
 # will see the following message at the end:
 #		"End of shell archive."
 # Contents:  gethostbyaddr.c gethostbyname.c
 # Wrapped by wietse@wzv on Sun Jan  8 17:08:48 1995
 PATH=/bin:/usr/bin:/usr/ucb ; export PATH
 if test -f gethostbyaddr.c -a "${1}" != "-c" ; then
   echo shar: Will not over-write existing file \"gethostbyaddr.c\"
 else
 echo shar: Extracting \"gethostbyaddr.c\" \(1073 characters\)
 sed "s/^X//" >gethostbyaddr.c <<'END_OF_gethostbyaddr.c'
 X /*
 X  * gethostbyaddr tester. compile with:
 X  *
 X  * cc -o gethostbyaddr gethostbyaddr.c (SunOS 4.x)
 X  *
 X  * cc -o gethostbyaddr gethostbyaddr.c -lnsl (SunOS 5.x)
 X  *
 X  * run as: gethostbyaddr address
 X  *
 X  * Author: Wietse Venema, Eindhoven University of Technology, The Netherlands.
 X  */
 X
 X#include <sys/types.h>
 X#include <sys/socket.h>
 X#include <netinet/in.h>
 X#include <arpa/inet.h>
 X#include <netdb.h>
 X#include <stdio.h>
 X
 Xmain(argc, argv)
 Xint     argc;
 Xchar  **argv;
 X{
 X    struct hostent *hp;
 X    long    addr;
 X
 X    if (argc != 2) {
 X	fprintf(stderr, "usage: %s i.p.addres\n", argv[0]);
 X	exit(1);
 X    }
 X    addr = inet_addr(argv[1]);
 X    if (hp = gethostbyaddr((char *) &addr, sizeof(addr), AF_INET)) {
 X	printf("Hostname:\t%s\n", hp->h_name);
 X	printf("Aliases:\t");
 X	while (hp->h_aliases[0])
 X	    printf("%s ", *hp->h_aliases++);
 X	printf("\n");
 X	printf("Addresses:\t");
 X	while (hp->h_addr_list[0])
 X	    printf("%s ", inet_ntoa(*(struct in_addr *) * hp->h_addr_list++));
 X	printf("\n");
 X	exit(0);
 X    }
 X    fprintf(stderr, "host %s not found\n", argv[1]);
 X    exit(1);
 X}
 END_OF_gethostbyaddr.c
 if test 1073 -ne `wc -c <gethostbyaddr.c`; then
     echo shar: \"gethostbyaddr.c\" unpacked with wrong size!
 fi
 # end of overwriting check
 fi
 if test -f gethostbyname.c -a "${1}" != "-c" ; then
   echo shar: Will not over-write existing file \"gethostbyname.c\"
 else
 echo shar: Extracting \"gethostbyname.c\" \(999 characters\)
 sed "s/^X//" >gethostbyname.c <<'END_OF_gethostbyname.c'
 X /*
 X  * gethostbyname tester. compile with:
 X  *
 X  * cc -o gethostbyname gethostbyname.c (SunOS 4.x)
 X  *
 X  * cc -o gethostbyname gethostbyname.c -lnsl (SunOS 5.x)
 X  *
 X  * run as: gethostbyname hostname
 X  *
 X  * Author: Wietse Venema, Eindhoven University of Technology, The Netherlands.
 X  */
 X#include <sys/types.h>
 X#include <sys/socket.h>
 X#include <netinet/in.h>
 X#include <arpa/inet.h>
 X#include <netdb.h>
 X#include <stdio.h>
 X
 Xmain(argc, argv)
 Xint     argc;
 Xchar  **argv;
 X{
 X    struct hostent *hp;
 X
 X    if (argc != 2) {
 X	fprintf(stderr, "usage: %s hostname\n", argv[0]);
 X	exit(1);
 X    }
 X    if (hp = gethostbyname(argv[1])) {
 X	printf("Hostname:\t%s\n", hp->h_name);
 X	printf("Aliases:\t");
 X	while (hp->h_aliases[0])
 X	    printf("%s ", *hp->h_aliases++);
 X	printf("\n");
 X	printf("Addresses:\t");
 X	while (hp->h_addr_list[0])
 X	    printf("%s ", inet_ntoa(*(struct in_addr *) * hp->h_addr_list++));
 X	printf("\n");
 X	exit(0);
 X    } else {
 X	fprintf(stderr, "host %s not found\n", argv[1]);
 X	exit(1);
 X    }
 X}
 END_OF_gethostbyname.c
 if test 999 -ne `wc -c <gethostbyname.c`; then
     echo shar: \"gethostbyname.c\" unpacked with wrong size!
 fi
 # end of overwriting check
 fi
 echo shar: End of shell archive.
 exit 0
	@(#) README.NIS 1.2 96/02/11 17:24:52

	> Problem: I have several [machines] with multiple IP addresses, and
	> when they try to connect to a daemon with tcp wrapper, they are often
	> rejected. I assume this is due to the -DPARANOID option, and depends
	> on which IP address is returned first from the nameserver for a given
	> name. This behavior seems to be random, may depend on ordering in
	> the YP host map?

	[Note: the situation described below no longer exists. Presently, my
	internet gateway uses the same IP address on all interfaces. To avoid
	confusion I have removed the old name wzv-gw.win.tue.nl from the DNS. I
	have kept the discussion below for educational reasons].

	NIS was not designed to handle multi-homed hosts. With NIS, each
	address should have its own hostname. For example, wzv-gw is my
	gateway. It has two interfaces: one connected to the local ethernet,
	the other to a serial link. In the NIS it is registered as:

	131.155.210.23 wzv-gw-ether
	131.155.12.78 wzv-gw-slip

	In principle, wzv-gw could be the official name of one of these
	interfaces, or it could be an alias for both.

	The DNS was designed to handle multi-homed hosts. In the DNS my gateway
	is registered in zone win.tue.nl, with one name that has two A records:

	wzv-gw IN A 131.155.210.23
	IN A 131.155.12.78

	And of course there are PTR records in zones 210.155.131.in-addr.arpa
	and 12.155.131.in-addr.arpa that point to wzv-gw.win.tue.nl.

	This setup does not cause any problems. You can test your name service
	with the two programs below. This is what they say on a local NIS client
	(both client and server running SunOS 4.1.3_U1):

	% gethostbyname wzv-gw
	Hostname: wzv-gw.win.tue.nl
	Aliases:
	Addresses: 131.155.210.23 131.155.12.78

	% gethostbyaddr 131.155.210.23
	Hostname: wzv-gw-ether
	Aliases:
	Addresses: 131.155.210.23

	% gethostbyaddr 131.155.12.78
	Hostname: wzv-gw-slip
	Aliases:
	Addresses: 131.155.12.78

	Things seem less confusing when seen by a NIS client in a different
	domain (both client and server running SunOS 4.1.3_U1):

	% gethostbyname wzv-gw.win.tue.nl
	Hostname: wzv-gw.win.tue.nl
	Aliases:
	Addresses: 131.155.210.23 131.155.12.78

	% gethostbyaddr 131.155.210.23
	Hostname: wzv-gw.win.tue.nl
	Aliases:
	Addresses: 131.155.12.78 131.155.210.23

	% gethostbyaddr 131.155.12.78
	Hostname: wzv-gw.win.tue.nl
	Aliases:
	Addresses: 131.155.210.23 131.155.12.78

	Alas, Solaris 2.4 still has problems. This is what I get on a Solaris
	2.4 NIS client, with a SunOS 4.1.3_U1 NIS server:

	% gethostbyname wzv-gw.win.tue.nl
	Hostname: wzv-gw.win.tue.nl
	Aliases: 131.155.210.23 wzv-gw.win.tue.nl
	Addresses: 131.155.12.78

	The tcpd source comes with a workaround for this problem. The
	workaround is ugly and is not part of the programs attached below.


	#! /bin/sh
	# This is a shell archive. Remove anything before this line, then unpack
	# it by saving it into a file and typing "sh file". To overwrite existing
	# files, type "sh file -c". You can also feed this as standard input via
	# unshar, or by typing "sh <file", e.g.. If this archive is complete, you
	# will see the following message at the end:
	# "End of shell archive."
	# Contents: gethostbyaddr.c gethostbyname.c
	# Wrapped by wietse@wzv on Sun Jan 8 17:08:48 1995
	PATH=/bin:/usr/bin:/usr/ucb ; export PATH
	if test -f gethostbyaddr.c -a "${1}" != "-c" ; then
	echo shar: Will not over-write existing file \"gethostbyaddr.c\"
	else
	echo shar: Extracting \"gethostbyaddr.c\" \(1073 characters\)
	sed "s/^X//" >gethostbyaddr.c <<'END_OF_gethostbyaddr.c'
	X /*
	X * gethostbyaddr tester. compile with:
	X *
	X * cc -o gethostbyaddr gethostbyaddr.c (SunOS 4.x)
	X *
	X * cc -o gethostbyaddr gethostbyaddr.c -lnsl (SunOS 5.x)
	X *
	X * run as: gethostbyaddr address
	X *
	X * Author: Wietse Venema, Eindhoven University of Technology, The Netherlands.
	X */
	X
	X#include <sys/types.h>
	X#include <sys/socket.h>
	X#include <netinet/in.h>
	X#include <arpa/inet.h>
	X#include <netdb.h>
	X#include <stdio.h>
	X
	Xmain(argc, argv)
	Xint argc;
	Xchar **argv;
	X{
	X struct hostent *hp;
	X long addr;
	X
	X if (argc != 2) {
	X fprintf(stderr, "usage: %s i.p.addres\n", argv[0]);
	X exit(1);
	X }
	X addr = inet_addr(argv[1]);
	X if (hp = gethostbyaddr((char *) &addr, sizeof(addr), AF_INET)) {
	X printf("Hostname:\t%s\n", hp->h_name);
	X printf("Aliases:\t");
	X while (hp->h_aliases[0])
	X printf("%s ", *hp->h_aliases++);
	X printf("\n");
	X printf("Addresses:\t");
	X while (hp->h_addr_list[0])
	X printf("%s ", inet_ntoa((struct in_addr ) * hp->h_addr_list++));
	X printf("\n");
	X exit(0);
	X }
	X fprintf(stderr, "host %s not found\n", argv[1]);
	X exit(1);
	X}
	END_OF_gethostbyaddr.c
	if test 1073 -ne `wc -c <gethostbyaddr.c`; then
	echo shar: \"gethostbyaddr.c\" unpacked with wrong size!
	fi
	# end of overwriting check
	fi
	if test -f gethostbyname.c -a "${1}" != "-c" ; then
	echo shar: Will not over-write existing file \"gethostbyname.c\"
	else
	echo shar: Extracting \"gethostbyname.c\" \(999 characters\)
	sed "s/^X//" >gethostbyname.c <<'END_OF_gethostbyname.c'
	X /*
	X * gethostbyname tester. compile with:
	X *
	X * cc -o gethostbyname gethostbyname.c (SunOS 4.x)
	X *
	X * cc -o gethostbyname gethostbyname.c -lnsl (SunOS 5.x)
	X *
	X * run as: gethostbyname hostname
	X *
	X * Author: Wietse Venema, Eindhoven University of Technology, The Netherlands.
	X */
	X#include <sys/types.h>
	X#include <sys/socket.h>
	X#include <netinet/in.h>
	X#include <arpa/inet.h>
	X#include <netdb.h>
	X#include <stdio.h>
	X
	Xmain(argc, argv)
	Xint argc;
	Xchar **argv;
	X{
	X struct hostent *hp;
	X
	X if (argc != 2) {
	X fprintf(stderr, "usage: %s hostname\n", argv[0]);
	X exit(1);
	X }
	X if (hp = gethostbyname(argv[1])) {
	X printf("Hostname:\t%s\n", hp->h_name);
	X printf("Aliases:\t");
	X while (hp->h_aliases[0])
	X printf("%s ", *hp->h_aliases++);
	X printf("\n");
	X printf("Addresses:\t");
	X while (hp->h_addr_list[0])
	X printf("%s ", inet_ntoa((struct in_addr ) * hp->h_addr_list++));
	X printf("\n");
	X exit(0);
	X } else {
	X fprintf(stderr, "host %s not found\n", argv[1]);
	X exit(1);
	X }
	X}
	END_OF_gethostbyname.c
	if test 999 -ne `wc -c <gethostbyname.c`; then
	echo shar: \"gethostbyname.c\" unpacked with wrong size!
	fi
	# end of overwriting check
	fi
	echo shar: End of shell archive.
	exit 0