home       inleiding       sysadmin       services       links       bash       werk       nothing      

DHCP daemon ( ubuntu 20 )

We beginnen met het opzetten van een testomgeving:

dhcp-service-linux2

 

  • 1 ubuntu20.04 met 2 netwerkkaarten: 1 kaart op NAT via DHCP // 1 kaart op intnet op 192.168.10.11/24
  • 1 w2k-client op intnet
     
    1. netwerk
      Het is nuttig de server eerst op te starten met slechts 1 netwerkkaart op NAT en die in te stellen als dhcp-client
       
      Daarna pas testen op de tweede netwerkkaart,
      ik zet die op 192.168.10.11/24:
       
      user@ubu20-04-001:~$ cat /etc/netplan/00-installer-config.yaml 
      # This is the network config written by 'subiquity'
network:
ethernets:
enp0s3:
dhcp4: true
enp0s8:     
addresses:
      - 192.168.10.11/24
version: 2

       
      ik herstart het netwerk:
       
      user@ubu204-dhcp:~$  sudo netplan apply
       
      Vervolgens controlleer ik met ifconfig:

      user@deb-91-dhcp:~$ ifconfig
enp0s3: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500
inet 10.0.2.15  netmask 255.255.255.0  broadcast 10.0.2.255
inet6 fe80::a00:27ff:fecc:edd0  prefixlen 64  scopeid 0x20<link>
ether 08:00:27:cc:ed:d0  txqueuelen 1000  (Ethernet)
RX packets 3613  bytes 2005449 (1.9 MiB)
RX errors 0  dropped 0  overruns 0  frame 0
TX packets 2821  bytes 343108 (335.0 KiB)
TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0
 
enp0s8: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500
inet 192.168.10.11  netmask 255.255.255.0  broadcast 192.168.10.255
inet6 fe80::a00:27ff:fe20:d5d5  prefixlen 64  scopeid 0x20<link>
ether 08:00:27:20:d5:d5  txqueuelen 1000  (Ethernet)
RX packets 156  bytes 25247 (24.6 KiB)
RX errors 0  dropped 0  overruns 0  frame 0
TX packets 43  bytes 5640 (5.5 KiB)
TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

       

    2. Installatie van dhcp-server:
      sudo apt-get install isc-dhcp-server
       
    3. configuratie van de netwerkkaart in dhcp-server:
      /etc/default/isc-dhcp-server 
      . . . 
# On what interfaces should the DHCP server (dhcpd) serve DHCP requests?
#   Separate multiple interfaces with spaces, e.g. "eth0 eth1".
INTERFACES="enp0s8"

       

    4. een minimum configuratie van de dhcp-server
       
      user@deb-91-dhcp:~$ cat /etc/dhcp/dhcpd.conf: 
      default-lease-time 600;
max-lease-time 7200;
subnet 192.168.10.0 netmask 255.255.255.0 {
}

       

    5. dhcp-server herstarten
       
      user@deb-91-dhcp:~$ sudo netplan apply
        
      soms krijg je dan rudimentaire foutmeldingen ...
        
      $ sudo systemctl restart isc-dhcp-server.service 
Job for isc-dhcp-server.service failed. See 'systemctl status isc-dhcp-server.service' and 'journalctl -xn' for details.

       
      met sudo less /var/log/syslog zie je wat er echt fout gegaan is >>> scrollen (of end toets) tot einde syslog.

      May 31 23:38:52 deb84 isc-dhcp-server[1600]: The error was:
May 31 23:38:52 deb84 dhcpd: Internet Systems Consortium DHCP Server 4.3.1
May 31 23:38:52 deb84 isc-dhcp-server[1600]: Internet Systems Consortium DHCP Server 4.3.1
May 31 23:38:52 deb84 dhcpd: Copyright 2004-2014 Internet Systems Consortium.
May 31 23:38:52 deb84 isc-dhcp-server[1600]: Copyright 2004-2014 Internet Systems Consortium.
May 31 23:38:52 deb84 dhcpd: All rights reserved.
May 31 23:38:52 deb84 isc-dhcp-server[1600]: All rights reserved.
May 31 23:38:52 deb84 dhcpd: For info, please visit https://www.isc.org/software/dhcp/
May 31 23:38:52 deb84 dhcpd: Config file: /etc/dhcp/dhcpd.conf
May 31 23:38:52 deb84 dhcpd: Database file: /var/lib/dhcp/dhcpd.leases
May 31 23:38:52 deb84 dhcpd: PID file: /var/run/dhcpd.pid
May 31 23:38:52 deb84 dhcpd: /etc/dhcp/dhcpd.conf line 23: expecting a declaration
May 31 23:38:52 deb84 dhcpd: };
May 31 23:38:52 deb84 dhcpd:  ^
May 31 23:38:52 deb84 dhcpd: Configuration file errors encountered -- exiting

       

    6. configureren
       
      Als je eindelijk een werkende dhcpd krijgt kun je de configuratie aanpassen tot bvb.: 
      ddns-update-style none;
option domain-name "example.org";
option domain-name-servers 10.28.100.20;
 
option subnet-mask 255.255.0.0;
default-lease-time 600;
max-lease-time 7200;
authoritative;
log-facility local7;
subnet 192.168.10.0 netmask 255.255.255.0 {
range 192.168.10.101 192.168.10.200;
}

       

    7. fixed IP op MAC-address 
        
      ddns-update-style none;
option domain-name "example.org";
option domain-name-servers 10.28.100.20;
option subnet-mask 255.255.0.0;
default-lease-time 600;
max-lease-time 7200;
authoritative;
log-facility local7;
#
# This is a very basic subnet declaration.
#
subnet 192.168.10.0 netmask 255.255.255.0 {
range 192.168.10.101 192.168.10.200;
# option routers rtr-239-0-1.example.org, rtr-239-0-2.example.org;
### STATIC IP LEASES ###
# w2k dhcp2 MAC: 08-00-27-92-49-3F
 
host w2k-dhcp2
         {
         hardware ethernet 08:00:27:92:49:3F;
         fixed-address 192.168.10.201;
         }
}

       

    8. leases controlleren
       
      user@deb-91-dhcp:~$ tail -n 15 /var/lib/dhcp/dhcpd.leases 
      # authoring-byte-order entry is generated, DO NOT DELETE
authoring-byte-order little-endian;
 
lease 192.168.10.101 {
starts 5 2018/02/23 12:33:08;
ends 5 2018/02/23 12:43:08;
cltt 5 2018/02/23 12:33:08;
binding state active;
next binding state free;
rewind binding state free;
hardware ethernet 08:00:27:6b:5e:d0;
uid "\001\010\000'k^\320";
set vendor-class-identifier = "MSFT 5.0";
client-hostname "vbox-w2k";
}