wiki-grav/pages/02.linux/dhcp-server-and-routing/default.en.md
2023-09-27 18:35:51 +02:00

161 lines
2.2 KiB
Markdown

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