---
name: "firehol-modifiers"
section: "5"
platform: "linux"
package: "firehol-doc"
version: "3.1.8+ds-1"
release: "Debian 13 (Trixie)"
platforms: ["linux"]
url: "https://new.carta.tech/firehol-modifiers"
---

# firehol-modifiers(5)

select IPv4 or IPv6 mode

## NAME

firehol-modifiers - select IPv4 or IPv6 mode

## SYNOPSIS

ipv4 *definition-or-command* *argument*...

ipv6 *definition-or-command* *argument*...

\[both\] *definition-or-command* *argument*...

## DESCRIPTION

When preceded by a modifier, any command or definition can be made to apply to IPv4 or IPv6 only.

Without a modifier, interface and router definitions and commands that come before either get applied to `both` IPv4 and IPV6.

Commands within an `interface` or `router` assume the same behaviour as the enclosing definition. You cannot create an IPv4 command within an IPv6 interface or router nor IPv6 within IPv4.

Examples:

-

  ```
   interface eth0 myboth src4 192.0.2.0/24 src6 2001:DB8::/24
     ipv4 server http accept
     ipv6 server http accept
   ipv4 interface eth0 my4only src 192.0.2.0/24
     server http accept
   ipv6 interface eth0 my6only src 2001:DB8::/24
     server http accept
  ```

Many definitions and commands have explicitly named variants (such as router4, router6, router46) which can be used as shorthand.

## SEE ALSO

- •

  [firehol(1)](/firehol/1.md) - FireHOL program

- •

  [firehol.conf(5)](/firehol.conf/5.md) - FireHOL configuration

- •

  [firehol-interface(5)](/firehol-interface/5.md) - interface definition

- •

  [firehol-router(5)](/firehol-router/5.md) - router definition

- •

  [firehol-policy(5)](/firehol-policy/5.md) - policy command

- •

  [firehol-protection(5)](/firehol-protection/5.md) - protection command

- •

  [firehol-server(5)](/firehol-server/5.md) - server, route commands

- •

  [firehol-client(5)](/firehol-client/5.md) - client command

- •

  [firehol-group(5)](/firehol-group/5.md) - group command

- •

  [firehol-iptables(5)](/firehol-iptables/5.md) - iptables helper

- •

  [firehol-masquerade(5)](/firehol-masquerade/5.md) - masquerade helper

- •

  FireHOL Website ⟨http://firehol.org/⟩\\c

- •

  FireHOL Online PDF Manual ⟨http://firehol.org/firehol-manual.pdf⟩\\c

- •

  FireHOL Online Documentation ⟨http://firehol.org/documentation/⟩\\c

## AUTHORS

FireHOL Team.