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Présentation:
DNS (Domain Name System) is used to make the correspondence between the IP address and machine name, it is called name resolution (to resolve into English). More concretely without DNS you would have to directly type the IP addresses of machines on which you want to access (web, ftp, telnet and others). If you are connected to an internet service provider (ISP) intermittently by PPP, ADSL or other, it's usually your ISP's DNS servers that provide name resolution, they usually go in pairs, one finds a primary DNS server and a secondary that is there in case of failure of the first.Now why configuring a DNS server on an isolated post, even on a small network of machines, because it can be used to solve a number of very annoying problems mostly found in off-line mode (not connected to the ISP ) including:- Launch of endless netscape or blocking at boot (for a period of 3min)- Sending mails in the folder waiting for sendmail that lasts more than a minute.But also if you have enabled ipmasquerade to share your Internet connection for your client, a DNS server allows them to surf and use the network tools (telnet, ftp, ...). Assume that your Linux machine, is called myhost and has IP address 192.168.13.10 (your private domain and not assigned by ISP) and your privacy mondomaine.fr. Trees presented (especially in the autostart) are those of a Mandrake (a priori as a RedHat).I will not go into details of the configuration files that you have the DNS-HOWTO (linux section and HOW-TO) which is a good introduction. This page is not intended to substitute for that document, it produces a summary to install a DNS server quickly, for detailed explanations see the HOWTO. It is primarily intended to an isolated post or even a small network connected in a non-permanent Internet.Note: If you do not know the IP addresses of DNS servers of your ISP, if automatic assignment of these addresses, for example, just log in and read the addresses at the nameserver lines.
Installing and configuring the server :
has set up a DNS server requires the installation of two tools bind and named. It concerns a Mandrake packages bind, caching-nameserver and bind-utils.
Linux for a client it will only benefit from the latest package for the host or dig commands. The installation created a file / etc / named.conf which is as follows: // generated by named-bootconf.pl
// secret must be the same as in /etc/rndc.conf
key "key" {
algorithm hmac-md5;
secret
"c3Ryb25nIGVub3VnaCBmb3IgYSBtYW4gYnV0IG1hZGUgZm9yIGEgd29tYW4K";
};
controls {
inet 127.0.0.1 allow { any; } keys { "key"; };
};
options {
pid-file "/var/run/named/named.pid";
directory "/var/named";
/*
* If there is a firewall between you and nameservers you want
* to talk to, you might need to uncomment the query-source
* directive below. Previous versions of BIND always asked
* questions using port 53, but BIND 8.1 uses an unprivileged
* port by default.
*/
// query-source address * port 53;
};
//
// a caching only nameserver config
//
zone "." {
type hint;
file "named.ca";
};
zone "0.0.127.in-addr.arpa" {
type master;
file "named.local";
};
On va le modifier pour lire:
// secret must be the same as in /etc/rndc.conf
key "key" {
algorithm hmac-md5;
secret
"c3Ryb25nIGVub3VnaCBmb3IgYSBtYW4gYnV0IG1hZGUgZm9yIGEgd29tYW4K";
};
controls {
inet 127.0.0.1 allow { any; } keys { "key"; };
};
options {
pid-file "/var/run/named/named.pid";
directory "/var/named";
/*
* If there is a firewall between you and nameservers you want
* to talk to, you might need to uncomment the query-source
* directive below. Previous versions of BIND always asked
* questions using port 53, but BIND 8.1 uses an unprivileged
* port by default.
*/
// query-source address * port 53;
// on va mettre ici l'adresses IP des serveurs DNS de vos FAI, votre serveur relaiera les requêtes à ceux-ci
// s'il n'est pas capable de les résoudre
forward first;
forwarders {
194.149.160.9;
194.149.160.1;
};
};
//
// a caching only nameserver config
//
zone "." {
type hint;
file "named.ca";
};
zone "0.0.127.in-addr.arpa" {
type master;
file "named.local";
};
zone "mondomaine.fr" {
type master;
file "mondomaine.fr";
};
The installation created a directory / var / named containing named.localLinux for a client it will only benefit from the latest package for the host or dig commands. The installation created a file / etc / named.conf which is as follows: // generated by named-bootconf.pl
// secret must be the same as in /etc/rndc.conf
key "key" {
algorithm hmac-md5;
secret
"c3Ryb25nIGVub3VnaCBmb3IgYSBtYW4gYnV0IG1hZGUgZm9yIGEgd29tYW4K";
};
controls {
inet 127.0.0.1 allow { any; } keys { "key"; };
};
options {
pid-file "/var/run/named/named.pid";
directory "/var/named";
/*
* If there is a firewall between you and nameservers you want
* to talk to, you might need to uncomment the query-source
* directive below. Previous versions of BIND always asked
* questions using port 53, but BIND 8.1 uses an unprivileged
* port by default.
*/
// query-source address * port 53;
};
//
// a caching only nameserver config
//
zone "." {
type hint;
file "named.ca";
};
zone "0.0.127.in-addr.arpa" {
type master;
file "named.local";
};
On va le modifier pour lire:
// secret must be the same as in /etc/rndc.conf
key "key" {
algorithm hmac-md5;
secret
"c3Ryb25nIGVub3VnaCBmb3IgYSBtYW4gYnV0IG1hZGUgZm9yIGEgd29tYW4K";
};
controls {
inet 127.0.0.1 allow { any; } keys { "key"; };
};
options {
pid-file "/var/run/named/named.pid";
directory "/var/named";
/*
* If there is a firewall between you and nameservers you want
* to talk to, you might need to uncomment the query-source
* directive below. Previous versions of BIND always asked
* questions using port 53, but BIND 8.1 uses an unprivileged
* port by default.
*/
// query-source address * port 53;
// on va mettre ici l'adresses IP des serveurs DNS de vos FAI, votre serveur relaiera les requêtes à ceux-ci
// s'il n'est pas capable de les résoudre
forward first;
forwarders {
194.149.160.9;
194.149.160.1;
};
};
//
// a caching only nameserver config
//
zone "." {
type hint;
file "named.ca";
};
zone "0.0.127.in-addr.arpa" {
type master;
file "named.local";
};
zone "mondomaine.fr" {
type master;
file "mondomaine.fr";
};
@ IN SOA localhost. root.localhost. (
1997022700 ; Serial
28800 ; Refresh
14400 ; Retry
3600000 ; Expire
86400 ) ; Minimum
IN NS localhost.
1 IN PTR localhost.
On le modifiera pour lire:
@ IN SOA mamachine.mondomaine.fr. root.mamachine.mondomaine.fr. (
1997022700 ; Serial
28800 ; Refresh
14400 ; Retry
3600000 ; Expire
86400 ) ; Minimum
IN NS mamachine.mondomaine.fr.
1 IN PTR localhost.
On créera sous /var/named un fichier mondomaine.fr contenant:
@ IN SOA mamachine.mondomaine.fr. root.mondomaine.fr. (
1997022700 ; Serial
28800 ; Refresh
14400 ; Retry
3600000 ; Expire
86400 ) ; Minimum
TXT "mondomaine.fr mon ch'tit domaine"
NS mamachine
NS mamachine.mondomaine.fr.
MX 10 mamachine
MX 20 mamachine.mondomaine.fr.
localhost A 127.0.0.1
mamachine A 192.168.13.10
Give this file named group named
chown named:named mondomaine.fr
FYI MX thus corresponds to the SMTP server to your machine if you are running sendmail.
Now in the / etc / nsswitch.conf must have it to the hosts line:
hosts: files dns
The DNS-HOWTO request the creation of a file / etc / host.conf containing
order hosts,bind
multi on
I do not know if it is absolutely necessary, it seems redundant with nsswitch.conf, but just in case.
To complete the / etc / resolv.conf:
search mondomaine.fr
nameserver 127.0.0.1
nameserver 194.149.160.9
nameserver 194.149.160.1
The last two IP addresses are obviously those of your favorite ISP. Note that in the case of an intermittent connection with ppp with automatic assignment of IP addresses of DNS servers, you can not change the last two lines, they are automatically populated when the connection.
Autostart of named
For a server installation on Mandrake, the configuration of the DNS server start automatic installation, you can skip this chapter. The default install of bind and named automatically generates startup files, just in case here are the details. You will find in / etc / rc.d / init.d named file has the following contents:#!/bin/sh
#
# named This shell script takes care of starting and stopping
# named (BIND DNS server).
#
# chkconfig: 345 55 45
# description: named (BIND) is a Domain Name Server (DNS) \
# that is used to resolve host names to IP addresses.
# probe: true
# Source function library.
. /etc/rc.d/init.d/functions
# Source networking configuration.
. /etc/sysconfig/network
# Check that networking is up.
[ ${NETWORKING} = "no" ] && exit 0
[ -f /usr/sbin/named ] || exit 0
[ -f /etc/named.conf ] || exit 0
# See how we were called.
case "$1" in
start)
# Start daemons.
echo -n "Starting named: "
daemon named
echo
touch /var/lock/subsys/named
;;
stop)
# Stop daemons.
echo -n "Shutting down named: "
killproc named
rm -f /var/lock/subsys/named
echo
;;
status)
/usr/sbin/ndc status
exit $?
;;
restart)
/usr/sbin/ndc restart
exit $?
;;
reload)
/usr/sbin/ndc reload
exit $?
;;
probe)
# named knows how to reload intelligently; we don't want linuxconf
# to offer to restart every time
/usr/sbin/ndc reload >/dev/null 2>&1 || echo start
exit 0
;;
*)
echo "Usage: named {start|stop|status|restart}"
exit 1
esac
exit 0
The DNS server is automatically started at power-on state 3, 4 and 5. It will still run after the installation by typing
/etc/rc.d/init.d/named start
To restart named (after a file change), you would type:
/ etc / rc.d / init.d / named restart
The other arguments are start, stop, restart and status.
Client Configuration:
Linux for a client, just create an / etc / resolv.conf containing
domain mondomaine.fr
nameserver 192.168.13.10
You replace it by the address of your server.
Do the same for windows clients, at the Panel and then Network icon.
Function tests:
From a Linux client or server host type the command in a shell, controls typing appear in italics: host -a mamachineTrying "mamachine.mondomaine.fr"
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 33741
;; flags: qr aa rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 1, ADDITIONAL: 0
;; QUESTION SECTION:
;mamachine.mondomaine.fr. IN ANY
;; ANSWER SECTION:
mamachine.mondomaine.fr. 86400 IN A 192.168.25.75
;; AUTHORITY SECTION:
mondomaine.fr. 86400 IN NS mamachine.mondomaine.fr.
Received 65 bytes from 127.0.0.1#53 in 15 ms
Then type:
host -a mondomaine.fr
Trying "mondomaine.fr"
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 47095
;; flags: qr aa rd ra; QUERY: 1, ANSWER: 5, AUTHORITY: 0, ADDITIONAL: 1
;; QUESTION SECTION:
;mondomaine.fr. IN ANY
;; ANSWER SECTION:
mondomaine.fr. 86400 IN SOA mamachine.mondomaine.fr. root.mondomaine.fr. 1997022700 28800 14400 3600000 86400
mondomaine.fr. 86400 IN TXT "mondomaine.fr mon ch'tit domaine"
mondomaine.fr. 86400 IN NS mamachine.mondomaine.fr.
mondomaine.fr. 86400 IN MX 10 mamachine.mondomaine.fr.
mondomaine.fr. 86400 IN MX 20 mamachine.mondomaine.fr.
;; ADDITIONAL SECTION:
mamachine.mondomaine.fr. 86400 IN A 192.168.25.75
Received 179 bytes from 127.0.0.1#53 in 21 ms
Once connected, a client or server type
host -a www.shom.fr
Trying "www.shom.fr."
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 12287
;; flags: qr rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 3, ADDITIONAL: 3
;; QUESTION SECTION:
;www.shom.fr. IN ANY
;; ANSWER SECTION:
www.shom.fr. 217813 IN CNAME cyclone.shom.fr.
;; AUTHORITY SECTION:
shom.fr. 330241 IN NS neree.shom.fr.
shom.fr. 330241 IN NS resone.univ-rennes1.fr.
shom.fr. 330241 IN NS dns.univ-lyon1.fr.
;; ADDITIONAL SECTION:
dns.univ-lyon1.fr. 317766 IN A 134.214.100.6
neree.shom.fr. 330241 IN A 194.57.228.65
resone.univ-rennes1.fr. 300271 IN A 129.20.254.1
Received 182 bytes from 192.168.25.75#53 in 157 ms
Le ping should work also.
From a position of windows to test your server in a Windows command prompt type
nslookup
At the prompt, type the name of machine under test
>www.shom.fr
Serveur: Unknown
Address: 192.168.26.75
Réponse de source secondaire :
Nom: cyclone.shom.fr
Address: 194.57.228.1
Aliases: www.shom.fr
Type CTRL + C to exit promptly at t
Create virtual hosts
You can create virtual hosts with your DNS server, in other words, your server may be identiifé by several names, it is particularly interesting for apache. With a different name that points to the same machine, however, we can point to different locations.Suppose we want to create virtual hosts www.idefix.mondomaine.fr et www.asterix.mondomaine.fr, on rajoutera à la fin du fichier /var/named/mondomaine.fr, the following lines:www.asterix A 192.168.13.11
www.idefix A 192.168.13.11
Restart the server by typing:
/etc/rc.d/init.d/named restart
To test a customer type in a shell:
ping www.asterix.mondomaine.fr
It should work.
