Методические материалы Лохтурова Вячеслава

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====== Сервис DHCP ======

  * [[https://ru.wikipedia.org/wiki/DHCP|Dynamic Host Configuration Protocol]]
  * [[https://www.isc.org/|Internet Systems Consortium, Inc. Mission-driven non-profit since 1994]]

  * [[https://www.vultr.com/docs/stop-dhcp-from-changing-resolve-conf/|Stop DHCP From Changing resolv.conf]]

  * [[https://www.isc.org/kea/|Kea DHCP Modern, open source DHCPv4 & DHCPv6 server]]

===== isc-dhcp-server =====

===== Установка =====

==== Debian/Ubuntu ====
<code>
root@gate:~# apt install isc-dhcp-server

root@gate:~# cat /etc/default/isc-dhcp-server
</code><code>
INTERFACESv4="eth0"
#INTERFACESv4="vlan2"
#INTERFACESv4="eth0 eth2"
</code>

==== CentOS ====

  * [[https://www.dmosk.ru/miniinstruktions.php?mini=dhcp-centos|Установка и настройка DHCP сервера на Linux CentOS 7]]

===== Настройка =====

==== Стандартная конфигурация ====
<code>
gate# cat /etc/dhcp/dhcpd.conf
</code><code>
ddns-update-style none;
log-facility local7;

default-lease-time 600;
max-lease-time 7200;

option domain-name "corpX.un";
#option domain-search "jet.msk.su","service.jet.msk.su","jetinf.jet.msk.su";
option domain-name-servers 192.168.X.10;
#option domain-name-servers 192.168.X.12;


#### For phone provisioning ####
#option file-server-name code 66 = string; # RFC 2132
#option file-server-address code 150 = ip-address; # RFC 5859 (Cisco)
#option file-server-name "server.corpX.un";
#option file-server-address 192.168.X.10;

#### For PXE ####
#allow booting;
#allow bootp;
#next-server 192.168.X.10;
#filename "pxelinux.0";
  
shared-network LAN1 {
  subnet 192.168.X.0 netmask 255.255.255.0 {
    range 192.168.X.101 192.168.X.109;
    option routers 192.168.X.1;
  }
}

#shared-network LAN2 {
#  subnet 192.168.113.0 netmask 255.255.255.0 {
#    range 192.168.113.101 192.168.113.109;
#    option routers 192.168.113.1;
#    next-server 192.168.X.10;
#    filename "pxe_lan2/pxelinux.0";
#  }
#}

#### For ip by mac ####
#host kube1 {hardware ethernet 08:00:27:12:34:51;fixed-address 192.168.X.221;}
#host kube2 {hardware ethernet 08:00:27:12:34:52;fixed-address 192.168.X.222;}
#host kube3 {hardware ethernet 08:00:27:12:34:53;fixed-address 192.168.X.223;}
#host kube4 {hardware ethernet 08:00:27:12:34:54;fixed-address 192.168.X.224;}

#### Digim D40 ####
#phone 407 {
#  hardware ethernet 00:0f:d3:06:11:d3; 
#  option file-server-name "http://server.corpX.un/";
#}
</code>

==== Отказоустойчивая конфигурация ====

  * !!! Синхронизируем время в системах !!! [[Сервис NTP]]
  * man dhcpd.conf (DHCP FAILOVER)
  * [[https://stevendiver.com/2020/02/21/isc-dhcp-failover-configuration/|ISC DHCP Failover Configuration]]

<code>
nodeN# cat /etc/dhcp/dhcpd.general
</code><code>
ddns-update-style none;

log-facility local7;

subnet 192.168.X.0 netmask 255.255.255.0 {
  pool {
    failover peer "dhcp";
    range 192.168.X.128 192.168.X.228;
  }
  option routers 192.168.X.254;
  option domain-name "corpX.un";
  option domain-name-servers 192.168.X.1, 192.168.X.2;
  default-lease-time 600;
  max-lease-time 7200;
}

#host node3 {hardware ethernet 08:00:27:12:34:53;fixed-address 192.168.X.3;}
#host node4 {hardware ethernet 08:00:27:12:34:54;fixed-address 192.168.X.4;}
#host node5 {hardware ethernet 08:00:27:12:34:55;fixed-address 192.168.X.5;}
#host node6 {hardware ethernet 08:00:27:12:34:56;fixed-address 192.168.X.6;}
#host node7 {hardware ethernet 08:00:27:12:34:57;fixed-address 192.168.X.7;}
</code>

<code>
node1# cat /etc/dhcp/dhcpd.conf
</code><code>
failover peer "dhcp" {
  primary;
  address 192.168.X.1;
  port 519;
  peer address 192.168.X.2;
  peer port 520;
  max-response-delay 60;
  max-unacked-updates 10;
  mclt 600;
  split 128;
  load balance max seconds 3;
}

include "/etc/dhcp/dhcpd.general";
</code>

<code>
node2# cat /etc/dhcp/dhcpd.conf
</code><code>
failover peer "dhcp" {
  secondary;
  address 192.168.X.2;
  port 520;
  peer address 192.168.X.1;
  peer port 519;
  max-response-delay 60;
  max-unacked-updates 10;
  load balance max seconds 3;
}

include "/etc/dhcp/dhcpd.general";
</code>

==== Конфигурация с поддержкой динамических обновлений зон DNS ====

  * Сервис DNS [[Сервис DNS#Настройка поддержки динамических обновлений от DHCP сервера]]
  * [[http://serverfault.com/questions/494523/adding-static-dns-entries-on-a-dynamic-bind-setup|Adding static DNS entries on a dynamic BIND setup]]

<code>
server# cat dhcpd.conf
</code><code>
ddns-update-style interim;
ddns-ttl 60;
...
subnet 192.168.X.0 netmask 255.255.255.0 {

### ubuntu
#include "/etc/dhcp/rndc.key";

### freebsd
#include "/usr/local/etc/rndc.key";

  zone corpX.un. {
    primary 192.168.X.10;
    key rndc-key;
  }
  zone X.168.192.in-addr.arpa. {
    primary 192.168.X.10;
    key rndc-key;
  }
...
</code>

===== Проверка конфигурации и запуск =====

==== Debian/Ubuntu ====
<code>
# dhcpd -t

# service isc-dhcp-server restart

# service isc-dhcp-server status
</code>

===== Сообщение от клиента, что кто-то уже занял IP =====
<code>
gate# journalctl -f
...
Mar 29 11:15:21 gate.corp13.un dhcpd[711]: Abandoning IP address 192.168.13.107: declined.
Mar 29 11:15:21 gate.corp13.un dhcpd[711]: DHCPDECLINE of 192.168.13.107 from 08:00:27:d5:6c:15 (client1) via eth0: abandoned
</code>
===== Мониторинг выданных адресов =====

  * [[https://stackoverflow.com/questions/2142824/parse-a-dhcpd-lease-file-with-bash|Parse a dhcpd.lease File with Bash]]
==== Debian/Ubuntu ====
<code>
root@gate:~# dhcp-lease-list

root@gate:~# less /var/lib/dhcp/dhcpd.leases

root@gate:~# grep dhcp /var/log/syslog
</code>

===== Статистика DHCP сервера =====

  * [[http://sourceforge.net/projects/dhcpd-pools/files/]]

==== Debian/Ubuntu ====
<code>
# apt install dhcpd-pools

# dhcpd-pools

# dhcpd-pools -l /var/lib/dhcp/dhcpd.leases -c /etc/dhcp/dhcpd.conf

# cat /usr/local/bin/dhcp_stat.sh
</code><code>
#!/bin/sh

CMD='/usr/bin/dhcpd-pools -l /var/lib/dhcp/dhcpd.leases -c /etc/dhcp/dhcpd.conf -f c | grep 192.168.'
MAX=`eval $CMD | cut -d'"' -f8`
CUR=`eval $CMD | cut -d'"' -f10`

eval RES=\$$1

echo $RES
</code><code>
# /usr/local/bin/dhcp_stat.sh MAX

# /usr/local/bin/dhcp_stat.sh CUR
</code>
==== FreeBSD ====
<code>
# pkg install dhcpd-pools

# dhcpd-pools -l /var/db/dhcpd/dhcpd.leases -c /usr/local/etc/dhcpd.conf
</code>

===== isc-kea =====

  * [[https://ubuntu.com/server/docs/how-to-install-and-configure-isc-kea|How to install and configure isc-kea]]

<code>
gate# apt install kea
...
... Do Nothing
...

gate# cat /etc/kea/kea-dhcp4.conf
</code><code>
{
"Dhcp4": {
    "interfaces-config": {
        "interfaces": [ "eth2" ],
        "dhcp-socket-type": "raw"
    },

    "control-socket": {
        "socket-type": "unix",
        "socket-name": "/run/kea/kea4-ctrl-socket"
    },

    "lease-database": {
        "type": "memfile",
        "lfc-interval": 3600
    },

    "expired-leases-processing": {
        "reclaim-timer-wait-time": 10,
        "flush-reclaimed-timer-wait-time": 25,
        "hold-reclaimed-time": 3600,
        "max-reclaim-leases": 100,
        "max-reclaim-time": 250,
        "unwarned-reclaim-cycles": 5
    },

    "renew-timer": 900,
    "rebind-timer": 1800,
    "valid-lifetime": 3600,

    "option-data": [
        {
            "name": "domain-name-servers",
            "data": "192.168.X.10"
        },
        # not work in windows
        {
            "name": "domain-search",
            "data": "corpX.un,isp.un"
        },
        {
            "name": "domain-name",
            "data": "corpX.un"
        }
    ],

    "subnet4": [
        {
            "id": 1,
            "subnet": "192.168.100+X.0/24",
            "pools": [ { "pool": "192.168.100+X.101 - 192.168.100+X.109" } ],
            "option-data": [
                {
                    "name": "routers",
                    "data": "192.168.100+X.1"
                }
            ]
        }
    ],
    "loggers": [
    {
        "name": "kea-dhcp4",
        "output_options": [
            {
                "output": "stdout",
                "pattern": "%-5p %m\n"
            }
        ],
        "severity": "INFO",
        "debuglevel": 0
    }
  ]
}
}
</code><code>
# kea-dhcp4 -t /etc/kea/kea-dhcp4.conf
  или
# sudo -u _kea kea-dhcp4 -t /etc/kea/kea-dhcp4.conf

# service kea-dhcp4-server restart

# service kea-dhcp4-server status

# cat /var/lib/kea/kea-leases4.csv
</code>

===== Поиск посторонних DHCP серверов =====

  * [[http://www.netpatch.ru/dhcdrop.html|Подавление DHCP серверов - dhcdrop]]

==== Debian/Ubuntu ====
<code>
# wget http://www.netpatch.ru/projects/dhcdrop/dhcdrop-lin-0.5.tar.bz2

# tar -xvf /root/dhcdrop-lin-0.5.tar.bz2 -C /usr/local/sbin/ dhcdrop
</code>

==== FreeBSD ====
<code>
# pkg install dhcdrop
</code>

==== FreeBSD/Debian/Ubuntu ====
<code>
# /usr/local/sbin/dhcdrop -b -i eth0 -c 2 -y

# /usr/local/sbin/dhcdrop -t -b -q -i <intface> -l <mac_address> > /tmp/dhcp.txt || (cat /tmp/dhcp.txt | mail -s 'Critical. Second DHCP.' root@corpX.un)
</code>
Методические материалы Лохтурова Вячеслава

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