What are FireHOL and FireQOS?

Aug 13, 2018 - FireHOL v3.1.6 released [more ...]

Apr 27, 2014 - I just wanted to thank you for ... [more ...]

FireHOL is a language (and a program to run it) which builds secure, stateful firewalls from easy to understand, human-readable configurations. The configurations stay readable even for very complex setups.

FireQOS is a program which sets up traffic shaping from an easy-to-understand and flexible configuration file.

Both programs abstract away the differences between IPv4 and IPv6. so you can concentrate on the rules you want. You can apply rules for IPv4 or IPv6, or both, as you need.

We think the best advert for these programs are their configurations. See below for:

The two programs are shipped together but work independently so you can choose to use one or both.


  • Make firewalling and traffic shaping an easy, straightforward task for everyone from end users to experienced administrators.
  • Be as secure as possible by allowing explicitly only the wanted traffic to flow.
  • Be a resource of knowledge around services and their peculiarities.
  • Be flexible enough for any firewalling or traffic-shaping need.
  • Be simple to install on any modern Linux system

Uses for FireHOL and FireQOS

Almost every Linux firewall / traffic control need is covered, including:

  • control of any number of internal/external/virtual interfaces
  • control of any combination of routed traffic
  • setting up DMZ routers and servers
  • all kinds of NAT
  • providing strong protection (flooding, spoofing, etc.)
  • transparent caches
  • source MAC verification
  • blacklists, whitelists
  • classification of traffic by source, destination and type
  • provide bandwidth guarantees and upper limits
  • allow optional borrowing of unused bandwidth
  • live stats on traffic classification


FireHOL is an iptables firewall generator producing stateful iptables packet filtering firewalls, on Linux hosts and routers with any number of network interfaces, any number of routes, any number of services served, any number of complexity between variations of the services (including positive and negative expressions).

Writing a complete, safe, firewall, suitable for protecting a host and a network can be this easy:

interface eth0 mylan policy accept interface ppp+ internet server smtp accept server http accept server ftp accept server ssh accept src example.firehol.org client all accept router mylan2internet inface eth0 outface ppp+ masquerade route all accept

Jump straight to the documentation to learn how to configure your own.

Hopefully you have noticed that all the rules given match just one direction of the traffic: the request. They don't say anything about replies. This is because FireHOL handles the replies automatically. You don't have to do anything about them: if a request is allowed, then the corresponding reply is also allowed. This also means that FireHOL produces the iptables statements to exactly match what is allowed in both directions and nothing more.

FireHOL is a language to express firewalling rules, not just a script that produces some kind of a firewall.

Is it secure?

FireHOL is secure because it has been designed with the right firewalling concept: deny everything, then allow only what is needed.

Also, FireHOL produces stateful iptables packet filtering firewalls (and possibly, the only generic tool today that does that for all services in both directions of the firewall).

Stateful means that traffic allowed to pass is part of a valid connection that has been initiated the right way. Stateful also means that you can have control based on who initiated the traffic. For example: you can choose to be able to ping anyone on the internet, but no one to be able to ping you. If for example you don't need to run a server on your Linux host, you can easily achieve a situation where you are able to do anything to anyone, but as far as the rest of world is concerned, you do not exist!

Learn another language?

FireHOL has been designed to allow you configure your firewall the same way you think of it. Its language is extremely simple. Basically you have to learn four commands:

  • interface, to setup a firewall on a network interface
  • router, to setup a firewall on traffic routed from one network interface to another
  • server, to setup a listening service within an interface or router. The same command can be used as route within routers
  • client, to setup a service client within an interface or router

Commands client and server have exactly the same syntax. A FireHOL interface has two mandatory arguments and a router has only one (and this is the same as one of the two that interface requires). All of the optional parameters are the same to all of them. This sounds like just one command is to be learned...

Of course there are a few more commands defined, but all of them exist just to give you finer control on these four.

If you don't believe it is simple, consider this example.


As an IT executive, responsible for many dozens of Linux systems, I needed a firewalling solution that would allow me and my team to have a clear and simple view of what is happening on each server, as far as firewalling is concerned. I also needed a solution that will allow my team members to produce high quality and homogeneous firewalls independently of their security skills and knowledge. After searching for such a tool, I quickly concluded that no tool is flexible, open, easy, and simple enough for what I needed.

I decided to write FireHOL in a way that will allow me, or anyone else, to view, verify and audit the firewall of any Linux server or Linux router in seconds. FireHOL's configuration is extremely simple... you don't have to be an expert to design a complicated but secure firewall.

What features does it have?

FireHOL handles firewalls protecting one host on all its interfaces and any combination of stateful firewalls routing traffic from one interface to another. There are no limitations on the number of interfaces or on the number of routing routes (except the ones iptables has, if any).

FireHOL, still lacks a few features: QoS for example is not supported directly. You are welcome to extend FireHOL and send me your patches to integrate within FireHOL. In any case however, you can embed normal iptables commands in a FireHOL configuration to do whatever iptables supports.

Since FireHOL produces stateful commands, for every supported service it needs to know the flow of requests and replies. Today FireHOL supports the following services:

  • Many single socket protocols, such as HTTP, NNTP, SMTP, POP3, IMAP4, RADIUS, SSH, LDAP, MySQL, Telnet, NTP, DNS, etc. There are a few dozens of such services defined in FireHOL. Check this list. Even if something is missing, you can define it.
  • Many complex protocols, such as FTP, NFS, SAMBA, PPTP, etc. If you need some complex protocol that is not present, you will have to program it (in simple Bash scripting - there are many commented examples on how this is done). Again, you will just create one Bash function with the rules of the protocol, and FireHOL will turn it to a client, a server or a router.


FireQOS is a traffic shaping helper. It has a very simple shell scripting language to express traffic shaping. You run FireQOS to setup the kernel commands. You can also run it to get status information or dump the traffic of a class. FireQOS is not a daemon and does not need to run always to apply traffic shaping.

Configuring a complete, functional, traffic shaping setup can be this easy:

LINKTYPE="adsl local pppoe-llc" server_rtp_ports="udp/10000:10100"
server_mytorrents_ports="any/60000:64999" interface ${DEVICE} world bidirectional ${LINKTYPE} input rate ${INPUT_SPEED} output rate ${OUTPUT_SPEED} class voip commit 110kbit pfifo server sip,rtp client sip,stun class interactive input commit 20% output commit 30% server dns,ssh,hangouts,icmp client dns,ssh,hangouts,gtalk,jabber,teamviewer,facetime class vpns input commit 20% output commit 30% server pptp,GRE class synacks commit 5% match tcp syn match tcp ack class surfing commit 5% client surfing,rsync class default class background commit 5% client torrents server mytorrents prio 1

Jump straight to the documentation to learn how to configure your own.

FireQOS also allows you to monitor the live status of traffic:

# ./sbin/fireqos.in status adsl-in
(C) 2013 Costa Tsaousis, GPL adsl-in: eth0 input => ifb0, type: adsl, overhead: 26
Rate: 10500Kbit/s, min: 105Kbit/s, R2Q: 8 (min rate 105Kbit/s)
Values in Kbit/s CLASS voip realtim clients torrent default
PRIORIT 1 2 3 5 4 COMMIT 105 1050 1050 105 105 MAX 10500 10500 10500 9450 9450 adsl-in (eth0 input => ifb0) - values in Kbit/s TOTAL voip realtim clients torrent default 46 - 7 - 39 - 50 - 5 - 42 3 80 - 9 - 60 11 75 - 6 - 65 4 103 19 3 - 79 2 56 - 3 - 50 3 84 - 5 - 70 9
  • FireQOS applies traffic shaping on the output of any interface.
  • FireQOS applies traffic shaping on the input of any interface. Shaping incoming traffic is classful, i.e. you have all the control available, similar to outgoing traffic. This is accomplished by setting up IFB devices. FireQOS handles everything about IFB devices. Any kernel that supports them will do.
  • FireQOS supports overheads calculation. This means it can perfectly shape incoming and outgoing traffic on a Linux box behind an ADSL router, or on a Linux box with an ADSL modem attached. ATM overheads will be calculated based on the DSL encapsulation.
  • FireQOS supports both IPv4 and IPv6. Each interface can be defined as ipv4, ipv6 or both (ipv4 and ipv6 in parallel).
  • FireQOS supports nested classes. Nested classes can either be direct (child classes are directly attached to their parent class), or hardware emulation (child classes are attached to a qdisc with linklayer parameters and overheads calculation, which is attached to a parent class).
  • FireQOS calculates port range masks (you just give a port range, FireQOS finds the optimal combination of tc statements to accomplish the match).
  • Virtually any number of interfaces, any number of classes and any number of classification rules can be configured (the way it is organised it can configure up to 5000 classes per interface).
  • It classifies packets using tc (both ipv4 and ipv6), but you can also use iptables CLASSIFY targets, or MARKs.
  • HTB is used for all classes.
  • FireQOS allows you to tcpdump the traffic of any leaf class. This allows you to examine the traffic you have assigned to classes.
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