ProHoster > Blog > Administration > Trin for trin vejledning til opsĂŠtning af DNS-server BIND i chroot-miljĂž for Red Hat (RHEL / CentOS) 7

Trin for trin vejledning til opsĂŠtning af DNS-server BIND i chroot-miljĂž for Red Hat (RHEL / CentOS) 7

OversÊttelsen af artiklen er forberedt til studerende pÄ kurset «Sikkerhed i Linux». Er du interesseret i at udvikle dig inden for dette omrÄde? Se optagelsen af Ivan Piskunovs masterclass «Sikkerhed i Linux sammenlignet med Windows og MacOS»

Trin for trin vejledning til opsĂŠtning af DNS-server BIND i chroot-miljĂž for Red Hat (RHEL / CentOS) 7

I denne artikel vil jeg beskrive trinene til at konfigurere en DNS-server pÄ RHEL 7 eller CentOS 7. For demonstration brugte jeg Red Hat Enterprise Linux 7.4. Vores mÄl er at oprette én A-post og én PTR-post til henholdsvis direktesyn og omvendt syn.

FĂžrst skal du installere de nĂždvendige rpm-pakker til DNS-serveren.

BEMÆRKNING: For RHEL skal du have en aktiv abonnement pĂ„ RHN, eller du kan konfigurere et lokalt offline-repository, som pakkeadministrator «yum» kan bruge til at installere de nĂždvendige rpm-pakker og afhĂŠngigheder.

# yum install bind bind-chroot caching-nameserver

Mine indstillinger:

# hostname
golinuxhub-client.example
ĐœĐŸĐč IP-аЎрДс 192.168.1.7
# ip address | egrep 'inet.*enp0s3'
    inet 192.168.1.7/24 brd 192.168.1.255 scope global dynamic enp0s3

Da vi vil bruge chroot, skal tjenesten deaktiveres.

# systemctl stop named
# systemctl disable named

Kopier derefter de nĂždvendige filer til chroot-kataloget.
BEMÆRKNING. Brug argumentet -p i kommandoen cp for at bevare rettigheder og ejerskab.

[root@golinuxhub-client ~]# cp -rpvf /usr/share/doc/bind-9.9.4/sample/etc/* /var/named/chroot/etc/
‘/usr/share/doc/bind-9.9.4/sample/etc/named.conf’ -> ‘/var/named/chroot/etc/named.conf’
‘/usr/share/doc/bind-9.9.4/sample/etc/named.rfc1912.zones’ -> ‘/var/named/chroot/etc/named.rfc1912.zones’

Kopier derefter zone-relaterede filer til det nye sted.

[root@golinuxhub-client ~]# cp -rpvf /usr/share/doc/bind-9.9.4/sample/var/named/* /var/named/chroot/var/named/
‘/usr/share/doc/bind-9.9.4/sample/var/named/data’ -> ‘/var/named/chroot/var/named/data’
‘/usr/share/doc/bind-9.9.4/sample/var/named/my.external.zone.db’ -> ‘/var/named/chroot/var/named/my.external.zone.db’
‘/usr/share/doc/bind-9.9.4/sample/var/named/my.internal.zone.db’ -> ‘/var/named/chroot/var/named/my.internal.zone.db’
‘/usr/share/doc/bind-9.9.4/sample/var/named/named.ca’ -> ‘/var/named/chroot/var/named/named.ca’
‘/usr/share/doc/bind-9.9.4/sample/var/named/named.empty’ -> ‘/var/named/chroot/var/named/named.empty’
‘/usr/share/doc/bind-9.9.4/sample/var/named/named.localhost’ -> ‘/var/named/chroot/var/named/named.localhost’
‘/usr/share/doc/bind-9.9.4/sample/var/named/named.loopback’ -> ‘/var/named/chroot/var/named/named.loopback’
‘/usr/share/doc/bind-9.9.4/sample/var/named/slaves’ -> ‘/var/named/chroot/var/named/slaves’
‘/usr/share/doc/bind-9.9.4/sample/var/named/slaves/my.ddns.internal.zone.db’ -> ‘/var/named/chroot/var/named/slaves/my.ddns.internal.zone.db’
‘/usr/share/doc/bind-9.9.4/sample/var/named/slaves/my.slave.internal.zone.db’ -> ‘/var/named/chroot/var/named/slaves/my.slave.internal.zone.db’

Nu lad os se pÄ hovedkonfigurationsfilen.

Ryd indholdet af named.conf og indsĂŠt fĂžlgende.

[root@golinuxhub-client etc]# vim named.conf
options {
        listen-on port 53 { 127.0.0.1; any; };
#       listen-on-v6 port 53 { ::1; };
        directory       "/var/named";
        dump-file       "/var/named/data/cache_dump.db";
        statistics-file "/var/named/data/named_stats.txt";
        memstatistics-file "/var/named/data/named_mem_stats.txt";
        allow-query     { localhost; any; };
        allow-query-cache { localhost; any; };
};

logging {
        channel default_debug {
                file "data/named.run";
                severity dynamic;
        };
};

view my_resolver {
        match-clients      { localhost; any; };
        recursion yes;
        include "/etc/named.rfc1912.zones";
};

Oplysninger relateret til zonen skal tilfĂžjes til /var/named/chroot/etc/named.rfc1912.zones. TilfĂžj posterne nedenfor. Filen example.zone er en fil til direkte visning, og example.rzone er filen til den omvendte zone.

VIGTIG BEMÆRKNING: Den omvendte visning indeholder 1.168.192, da min IP-adresse er 192.168.1.7

zone "example" IN {
        type master;
        file "example.zone";
        allow-update { none; };
};

zone "1.168.192.in-addr.arpa" IN {
        type master;
        file "example.rzone";
        allow-update { none; };
};

Filer relateret til zoner findes her:

# cd /var/named/chroot/var/named/

Lad os nu oprette filer til den direkte og omvendte zone. Filnavnene vil vĂŠre de samme som tidligere i filen named.rfc1912.zones. Vi har allerede nogle standard skabeloner, som vi kan bruge.

# cp -p named.localhost  example.zone
# cp -p named.loopback example.rzone

Som du kan se, er de nuvĂŠrende rettigheder for alle filer og mapper ejet af root.

[root@golinuxhub-client named]# ll
total 32
drwxr-xr-x. 2 root root    6 May 22  2017 data
-rw-r--r--. 1 root root  168 May 22  2017 example.rzone
-rw-r--r--. 1 root root  152 May 22  2017 example.zone
-rw-r--r--. 1 root root   56 May 22  2017 my.external.zone.db
-rw-r--r--. 1 root root   56 May 22  2017 my.internal.zone.db
-rw-r--r--. 1 root root 2281 May 22  2017 named.ca
-rw-r--r--. 1 root root  152 May 22  2017 named.empty
-rw-r--r--. 1 root root  152 May 22  2017 named.localhost
-rw-r--r--. 1 root root  168 May 22  2017 named.loopback
drwxr-xr-x. 2 root root   71 Feb 12 21:02 slaves

Ændr rettighederne for alle filer ved at angive brugeren som root og gruppen named.

# chown root:named *

Men for data skal ejeren vĂŠre named:named.

# chown -R  named:named data
# ls -l
total 32
drwxr-xr-x. 2 named named    6 May 22  2017 data
-rw-r--r--. 1 root  named  168 May 22  2017 example.rzone
-rw-r--r--. 1 root  named  152 May 22  2017 example.zone
-rw-r--r--. 1 root  named   56 May 22  2017 my.external.zone.db
-rw-r--r--. 1 root  named   56 May 22  2017 my.internal.zone.db
-rw-r--r--. 1 root  named 2281 May 22  2017 named.ca
-rw-r--r--. 1 root  named  152 May 22  2017 named.empty
-rw-r--r--. 1 root  named  152 May 22  2017 named.localhost
-rw-r--r--. 1 root  named  168 May 22  2017 named.loopback
drwxr-xr-x. 2 root  named   71 Feb 12 21:02 slaves

TilfĂžj indholdet nedenfor til filen til den direkte zone. Her opretter vi A-poster for localhost (golinuxhub-client) og en anden for serveren (golinuxhub-server).

# vim example.zone
$TTL 1D
@       IN SOA  example. root (
                                        1       ; serial
                                        3H      ; refresh
                                        15M     ; retry
                                        1W      ; expire
                                        1D )    ; minimum

                IN NS           example.

                        IN A 192.168.1.7
golinuxhub-server       IN A 192.168.1.5
golinuxhub-client       IN A 192.169.1.7

TilfĂžj derefter indholdet til filen for den omvendte zone. Her opretter vi en PTR-post for golinuxhub-client og for serveren golinuxhub-server.

# vim example.rzone
$TTL 1D
@       IN SOA  example. root.example. (
                                        1997022700      ; serial
                                        28800           ; refresh
                                        14400           ; retry
                                        3600000         ; expire
                                        86400  )        ; minimum

        IN NS   example.
5       IN PTR  golinuxhub-server.example.
7       IN PTR  golinuxhub-client.example.

FĂžr vi starter tjenesten named-chroot, kontrollerer vi konfigurationen af zonefilen.

[root@golinuxhub-client named]# named-checkzone golinuxhub-client.example example.zone
zone golinuxhub-client.example/IN: loaded serial 1
OK

[root@golinuxhub-client named]# named-checkzone golinuxhub-client.example example.rzone
zone golinuxhub-client.example/IN: loaded serial 1997022700
OK

Alt ser godt ud. Tjek nu konfigurationsfilen ved hjĂŠlp af fĂžlgende kommando.

[root@golinuxhub-client named]# named-checkconf -t /var/named/chroot/ /etc/named.conf

SĂ„ alt blev udfĂžrt med succes.

[root@golinuxhub-client named]# echo $?
0

VIGTIG BEMÆRKNING: Jeg har SELinux i permissive tilstand

# getenforce
Permissive

Alt ser godt ud, sÄ det er tid til at starte vores tjeneste named-chroot .

[root@golinuxhub-client named]# systemctl restart named-chroot

[root@golinuxhub-client named]# systemctl status named-chroot
● named-chroot.service - Berkeley Internet Name Domain (DNS)
   Loaded: loaded (/usr/lib/systemd/system/named-chroot.service; disabled; vendor preset: disabled)
   Active: active (running) since Mon 2018-02-12 21:53:23 IST; 19s ago
  Process: 5236 ExecStop=/bin/sh -c /usr/sbin/rndc stop > /dev/null 2>&1 || /bin/kill -TERM $MAINPID (code=exited, status=0/SUCCESS)
  Process: 5327 ExecStart=/usr/sbin/named -u named -c ${NAMEDCONF} -t /var/named/chroot $OPTIONS (code=exited, status=0/SUCCESS)
  Process: 5325 ExecStartPre=/bin/bash -c if [ ! "$DISABLE_ZONE_CHECKING" == "yes" ]; then /usr/sbin/named-checkconf -t /var/named/chroot -z "$NAMEDCONF"; else echo "Kontrol af zoner er deaktiveret"; fi (code=exited, status=0/SUCCESS)
 Main PID: 5330 (named)
   CGroup: /system.slice/named-chroot.service
           └─5330 /usr/sbin/named -u named -c /etc/named.conf -t /var/named/chroot

Feb 12 21:53:23 golinuxhub-client.example named[5330]: managed-keys-zone/my_resolver: loaded serial 0
Feb 12 21:53:23 golinuxhub-client.example named[5330]: zone 0.in-addr.arpa/IN/my_resolver: loaded serial 0
Feb 12 21:53:23 golinuxhub-client.example named[5330]: zone 1.0.0.127.in-addr.arpa/IN/my_resolver: loaded serial 0
Feb 12 21:53:23 golinuxhub-client.example named[5330]: zone 1.168.192.in-addr.arpa/IN/my_resolver: loaded serial 1997022700
Feb 12 21:53:23 golinuxhub-client.example named[5330]: zone example/IN/my_resolver: loaded serial 1
Feb 12 21:53:23 golinuxhub-client.example named[5330]: zone localhost/IN/my_resolver: loaded serial 0
Feb 12 21:53:23 golinuxhub-client.example named[5330]: zone 1.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.ip6.arpa/IN/my_resolver: loaded serial 0
Feb 12 21:53:23 golinuxhub-client.example named[5330]: zone localhost.localdomain/IN/my_resolver: loaded serial 0
Feb 12 21:53:23 golinuxhub-client.example named[5330]: all zones loaded
Feb 12 21:53:23 golinuxhub-client.example named[5330]: running
```bash
SÞrg for, at resolv.conf indeholder din IP-adresse, sÄ den kan fungere som en DNS-server.
```bash
# cat /etc/resolv.conf
search example
nameserver 192.168.1.7
```bash
Lad os kontrollere vores DNS-server for den omvendte zone ved at bruge dig.
```bash
[root@golinuxhub-client named]# dig -x 192.168.1.5

; <> DiG 9.9.4-RedHat-9.9.4-50.el7 <> -x 192.168.1.5
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 40331
;; flags: qr aa rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 1, ADDITIONAL: 2

;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 4096
;; QUESTION SECTION:
;5.1.168.192.in-addr.arpa.      IN      PTR

;; ANSWER SECTION:
5.1.168.192.in-addr.arpa. 86400 IN      PTR     golinuxhub-server.example.

;; AUTHORITY SECTION:
1.168.192.in-addr.arpa. 86400   IN      NS      example.

;; ADDITIONAL SECTION:
example.                86400   IN      A       192.168.1.7

;; Query time: 1 msec
;; SERVER: 192.168.1.7#53(192.168.1.7)
;; WHEN: Mon Feb 12 22:13:17 IST 2018
;; MSG SIZE  rcvd: 122

Som du kan se, har vi fÄet et positivt svar (ANSWER) pÄ vores forespÞrgsel (QUERY).

[root@golinuxhub-client named]# dig -x 192.168.1.7

; <> DiG 9.9.4-RedHat-9.9.4-50.el7 <> -x 192.168.1.7
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 55804
;; flags: qr aa rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 1, ADDITIONAL: 2

;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 4096
;; QUESTION SECTION:
;7.1.168.192.in-addr.arpa.      IN      PTR

;; ANSWER SECTION:
7.1.168.192.in-addr.arpa. 86400 IN      PTR     golinuxhub-client.example.

;; AUTHORITY SECTION:
1.168.192.in-addr.arpa. 86400   IN      NS      example.

;; ADDITIONAL SECTION:
example.                86400   IN      A       192.168.1.7

;; Query time: 1 msec
;; SERVER: 192.168.1.7#53(192.168.1.7)
;; WHEN: Mon Feb 12 22:12:54 IST 2018
;; MSG SIZE  rcvd: 122

PÄ samme mÄde kan vi kontrollere den direkte zone.

[root@golinuxhub-client named]# nslookup golinuxhub-client.example
Server:         192.168.1.7
Address:        192.168.1.7#53

Name:   golinuxhub-client.example
Address: 192.169.1.7

[root@golinuxhub-client named]# nslookup golinuxhub-server.example
Server:         192.168.1.7
Address:        192.168.1.7#53

Name:   golinuxhub-server.example
Address: 192.168.1.5

Denne artikel er lidt forĂŠldet, da der i RHEL 7 ikke lĂŠngere er behov for at kopiere bind konfigurationsfiler til chroot. Trin-for-trin vejledning: Konfigurer DNS-server ved hjĂŠlp af bind chroot (CentOS/RHEL 7).

Kilde: habr.com

KĂžb pĂ„lidelig webhosting med DDoS-beskyttelse, VPS VDS-servere đŸ”„ KĂžb pĂ„lidelig webhosting med DDoS-beskyttelse, VPS VDS-servere | ProHoster