dnsmasq

https://thekelleys.org.uk/dnsmasq/docs/dnsmasq-man.html
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dnsmasq provides DNS forwarding and caching, DHCP services, and network boot support for small...
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### Basic Authoritative Server Setup

Source: https://thekelleys.org.uk/dnsmasq/docs/dnsmasq-man.html

Configure dnsmasq to act as an authoritative server for a specific domain and listen on a network interface.

```dnsmasq
--auth-server=server.example.com,eth0
--auth-zone=our.zone.com,1.2.3.0/24
```

--------------------------------

### Authoritative Server with Internal IP Record

Source: https://thekelleys.org.uk/dnsmasq/docs/dnsmasq-man.html

A more complex setup where the authoritative server's own IP address is within the zone it serves, solving the chicken-and-egg problem for glue records.

```dnsmasq
--auth-server=our.zone.com,eth0
--auth-zone=our.zone.com,1.2.3.0/24
```

--------------------------------

### Enable TFTP Server

Source: https://thekelleys.org.uk/dnsmasq/docs/dnsmasq-man.html

Enable the TFTP server function for net-booting clients. Supports reading with tsize and blksize extensions.

```bash
--enable-tftp[= <interface>[,<interface>]]
```

--------------------------------

### Prevent TFTP Startup Failure on Inaccessible Roots

Source: https://thekelleys.org.uk/dnsmasq/docs/dnsmasq-man.html

Do not abort startup if specified tftp root directories are inaccessible.

```bash
--tftp-no-fail
```

--------------------------------

### Configure Router Advertisement Parameters

Source: https://thekelleys.org.uk/dnsmasq/docs/dnsmasq-man.html

Set non-default values for router advertisements sent via an interface, including priority, interval, lifetime, and MTU.

```bash
--ra-param=eth0,high
```

```bash
--ra-param=eth0,60
```

```bash
--ra-param=eth0,0,0
```

```bash
--ra-param=eth0,mtu:1280,low,60,1200
```

--------------------------------

### Configure DHCP Host with Static IP and Lease Time

Source: https://thekelleys.org.uk/dnsmasq/docs/dnsmasq-man.html

Assign a specific IP address and infinite lease time to a host identified by its MAC address. This overrides any hostname provided by the DHCP client.

```bash
--dhcp-host=00:20:e0:3b:13:af,wap,infinite
```

--------------------------------

### Set TFTP Root Directory

Source: https://thekelleys.org.uk/dnsmasq/docs/dnsmasq-man.html

Specify the directory for TFTP transfer files. Paths with '..' are rejected. Absolute paths must be within the root. Can be interface-specific.

```bash
--tftp-root= <directory>[,<interface>]
```

--------------------------------

### Add Client IP or MAC to TFTP Root Path

Source: https://thekelleys.org.uk/dnsmasq/docs/dnsmasq-man.html

Appends the client's IP or MAC address to the TFTP root path for unique client directories. Defaults to IP address.

```bash
--tftp-unique-root[=ip|mac]
```

--------------------------------

### Enable TFTP Secure Mode

Source: https://thekelleys.org.uk/dnsmasq/docs/dnsmasq-man.html

Restricts TFTP access to files owned by the dnsmasq user. If running as root, only world-readable files are accessible.

```bash
--tftp-secure
```

--------------------------------

### Configuring Reverse DNS Lookup

Source: https://thekelleys.org.uk/dnsmasq/docs/dnsmasq-man.html

Sets up reverse DNS lookups for a subnet by adding an NS record pointing to the authoritative server.

```dnsmasq
3.2.1.in-addr.arpa  NS    our.zone.com
```

--------------------------------

### Assign IPv6 Address with Prefix Length

Source: https://thekelleys.org.uk/dnsmasq/docs/dnsmasq-man.html

Specify an IPv6 address with a prefix length, allowing for a range of addresses to be allocated. This is useful for scenarios like chain netbooting where a host may obtain multiple addresses.

```bash
--dhcp-host=laptop,[1234:50/126]
```

--------------------------------

### Set TFTP MTU Size

Source: https://thekelleys.org.uk/dnsmasq/docs/dnsmasq-man.html

Use the specified size as the ceiling of the MTU for negotiating TFTP blocksize, overriding the local interface MTU if larger.

```bash
--tftp-mtu= <mtu size>
```

--------------------------------

### Assign IPv4 and IPv6 Addresses to a DHCP Host

Source: https://thekelleys.org.uk/dnsmasq/docs/dnsmasq-man.html

Configure a host with both IPv4 and IPv6 addresses. IPv6 addresses must be enclosed in square brackets.

```bash
--dhcp-host=laptop,[1234::56]
```

--------------------------------

### Assign Static IP to a Host by Hostname

Source: https://thekelleys.org.uk/dnsmasq/docs/dnsmasq-man.html

Always allocate a specific IP address to a host identified by its hostname. This is useful for machines that do not provide a consistent MAC address.

```bash
--dhcp-host=lap,192.168.0.199
```

--------------------------------

### Set TFTP Port Range

Source: https://thekelleys.org.uk/dnsmasq/docs/dnsmasq-man.html

Define the range of ports for TFTP connections.

```bash
--tftp-port-range= <start>,<end>
```

--------------------------------

### Delay DHCP Offer and ProxyDHCP Replies

Source: https://thekelleys.org.uk/dnsmasq/docs/dnsmasq-man.html

Delays sending DHCPOFFER and PROXYDHCP replies for at least the specified number of seconds. Useful for PXE boot firmware bugs.

```bash
--dhcp-reply-delay=[tag: <tag>,]<integer>
```

--------------------------------

### Authoritative Server with Dynamic IP Handling

Source: https://thekelleys.org.uk/dnsmasq/docs/dnsmasq-man.html

Handles dynamic external IP addresses by using --interface-name to associate the server's domain name with the IP address of a specified interface.

```dnsmasq
--auth-server=our.zone.com,eth0
--interface-name=our.zone.com,eth0
--auth-zone=our.zone.com,1.2.3.0/24,eth0
```

--------------------------------

### Ignore Client-ID and Use MAC Address for DHCPv4

Source: https://thekelleys.org.uk/dnsmasq/docs/dnsmasq-man.html

For DHCPv4, use the special option 'id:*' to ignore any client-ID provided by the client and rely solely on MAC addresses. This is helpful when clients inconsistently provide a client-ID.

```bash
id:*
```

--------------------------------

### Set Maximum Concurrent TFTP Connections

Source: https://thekelleys.org.uk/dnsmasq/docs/dnsmasq-man.html

Set the maximum number of concurrent TFTP connections allowed. Defaults to 50.

```bash
--tftp-max= <connections>
```

--------------------------------

### Authoritative Server with Static Host Record

Source: https://thekelleys.org.uk/dnsmasq/docs/dnsmasq-man.html

Configures an authoritative server using a static host record for the server's IP address, suitable for static external IP configurations.

```dnsmasq
--auth-server=our.zone.com,eth0
--host-record=our.zone.com,1.2.3.4
--auth-zone=our.zone.com,1.2.3.0/24
```

--------------------------------

### Adding Secondary DNS Server Configuration

Source: https://thekelleys.org.uk/dnsmasq/docs/dnsmasq-man.html

Configures dnsmasq to act as a primary authoritative server and specifies a secondary server for zone transfers.

```dnsmasq
--auth-sec-servers=secondary.myisp.com
```

--------------------------------

### Assign DHCP Host Parameters using Client Identifier

Source: https://thekelleys.org.uk/dnsmasq/docs/dnsmasq-man.html

Specify DHCP host parameters using a client identifier (DUID for IPv6) instead of a hardware address. This is useful for clients that may not consistently provide a MAC address.

```bash
--dhcp-host=id:01:02:03:04,.....
```

```bash
--dhcp-host=id:clientidastext,.....
```

--------------------------------

### Convert TFTP Filenames to Lowercase

Source: https://thekelleys.org.uk/dnsmasq/docs/dnsmasq-man.html

Converts filenames in TFTP requests to all lowercase. Useful for case-insensitive filesystems like Windows.

```bash
--tftp-lowercase
```

--------------------------------

### Assign IPv6 Address with Host Identifier Only

Source: https://thekelleys.org.uk/dnsmasq/docs/dnsmasq-man.html

Specify an IPv6 address using only the host-identifier part. Dnsmasq will insert the appropriate network part, acting as a wildcard in constructed DHCP ranges.

```bash
--dhcp-host=laptop,[::56]
```

--------------------------------

### Disable TFTP Blocksize Negotiation

Source: https://thekelleys.org.uk/dnsmasq/docs/dnsmasq-man.html

Stops the TFTP server from negotiating the 'blocksize' option with a client, useful for buggy clients.

```bash
--tftp-no-blocksize
```

--------------------------------

### Wildcard CNAME Record

Source: https://thekelleys.org.uk/dnsmasq/docs/dnsmasq-man.html

Defines a wildcard CNAME record within an authoritative domain, allowing any subdomain to resolve to a default target.

```dnsmasq
--cname=*.example.com,default.example.com
```
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