161 lines
2.2 KiB
Markdown
161 lines
2.2 KiB
Markdown
---
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title: "DHCP Server and Routing"
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visible: true
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---
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[toc]
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## Installation
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[shroot]
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```sh
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apt install isc-dhcp-server
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```
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[/shroot]
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## Configuration
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Edit `/etc/default/isc-dhcp-server`
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```
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INTERFACESv4="[INTERFACE 1] [INTERFACE 2]"
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```
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Edit `/etc/dhcp/dhcpd.conf` to set a subnet
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```
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subnet [NETADDRESS] netmask [SUBNETMASK] {
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range [FIRST DHCP] [LAST DHCP];
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option subnet-mask [SUBNETMASK];
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option routers [GATEWAY];
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option domain-name "[NAME]";
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option domain-name-servers [DNS SERVER];
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}
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```
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Edit `/etc/network/interfaces`
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```
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auto [INTERFACE]
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iface [INTERFACE] inet static
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address [ADDRESS]
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network [NETADDRESS]
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netmask [NETMASK]
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broadcast [BROADCAST]
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```
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Enable the interface
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[shroot]
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```sh
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ifup [INTERFACE]
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```
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[/shroot]
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Restart DHCP Server
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[shroot]
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```sh
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systemctl restart isc-dhcp-server.service
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```
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[/shroot]
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### Enable routing
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[shroot]
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```sh
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echo "net.ipv4.ip_forward=1" >> /etc/sysctl.d/80-forwarding.conf
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sysctl -p /etc/sysctl.d/80-forwarding.conf
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```
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[/shroot]
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[shroot]
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```sh
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iptables -t nat -A POSTROUTING -o [WAN INTERFACE] -j MASQUERADE
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iptables -A FORWARD -i [LAN INTERFACE] -j ACCEPT
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```
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[/shroot]
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Make iptables permanent
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Select `Yes` during the installation to save current rules
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[shroot]
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```sh
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apt install iptables-persistent
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```
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[/shroot]
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### Enable DHCP-managed fixed IP address
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```
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host [HOSTNAME] {
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hardware ethernet [MAC ADDRESS];
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fixed-address [IP ADDRESS];
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}
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```
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### Dynamic DNS
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_Needs a supported DNS like BIND or PowerDNS_
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[Configure your DNS server to accept updates](/linux/services/powerdns)
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Add the following snippet to your `/etc/dhcp/dhcpd.conf` file
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How to generate the key is also described in the DNS article
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```
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ddns-updates on;
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ddns-update-style interim;
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update-static-leases on;
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ddns-domainname "testpdns";
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ddns-rev-domainname "in-addr.arpa.";
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key "[KEYNAME]" {
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algorithm hmac-md5;
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secret "[KEY]";
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};
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zone testpdns {
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primary 127.0.0.1;
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key [KEYNAME];
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}
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zone 7.168.192.in-addr.arpa. {
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primary 127.0.0.1;
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key [KEYNAME];
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}
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```
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## Client
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DHCP Request
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[shroot]
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```sh
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dhclient -v
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```
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[/shroot]
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Release IP
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[shroot]
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```sh
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dhclient -v -r
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```
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[/shroot]
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