This page answers some Frequently Asked Questions about Freetz. It is still under construction.

Be aware that there is a more complete FAQ version in German.


  1. Project name and history
    1. What is Freetz?
    2. Where does the name Freetz come from?
    3. How should I pronounce Freetz?
    4. How did Freetz start?
    5. Why change the name when DS-Mod has already become well-known?
    6. Why is so much of Freetz and the development in German?
  2. Motivation
    1. Why change the firmware?
  3. Distribution
    1. Can I get a finished binary of Freetz?
    2. How can I get Freetz?
    3. Which type of boxes and which firmware versions are currently supported?:
  4. Development
    1. When will version xy be released?
    2. Trunk, Branches, Tags?
    3. When feature XY is implemented?
    4. I like Freetz and I want to support the development.
  5. Pre-Configuration (menuconfig)
    1. Do I have the 8MB (v1) or 16MB (v2) version of the FB 7270 ?
    2. What are indicators for a FB 7270v3 ?
    3. Which packages should be built into a Freetz image ?
    4. What does "binary only" mean ?
  6. Image Build (make/build)
    1. Meaning of the specific make-targets
    2. Building another firmware language
    3. Problems during building
    4. The problem still occurs. What now?
  7. Flashing of Compiled Image
  8. Problems after (successful) Flashing
    1. Settings are not available at current security level
    2. What is the default password for freetz?
    3. The info led blinks twice periodically
  9. Configuration
    1. Were is the whole configuration stored on the Fritzbox ?
    2. Configuration not available at the current security level!
    3. How can i disable the password for the Freetz-Website?
    4. How can i change the password for the Freetz-Website?
    5. How can i reset the password for the Freetz-Website in case I've lost it …
    6. How can I change the root-Password?
  10. Problems During Working
    1. /var/flash/freetz too big
    2. No ftp access after Freetz
  11. Removing FREETZ and Other Modifications
  12. Miscellaneous
    1. How can I use an own/other DNS server for all connected PCs and Fritzbox ?
    2. How can I create character devices ?
    3. Which network cable is necessary for a recover ?
    4. How old is my FritzBox ?
    5. How much RAM does my FritzBox contain?

Project name and history

What is Freetz?

Freetz is a toolbox for developers and experienced users to build a modified firmware based on the original firmware for the DSL/LAN/WLAN/VoIP-Routers AVM Fritz!Box and T-Com Speedport (identical hardware) and to transfer this firmware to the device. There are many extension packages available, along with options to remove unwanted functionality from the original firmware.

Where does the name Freetz come from?

It is a contraction of the word "free" and the name "Fritz", intended to mirror the name of the devices manufactured by AVM . With this, we want to symbolise that Freetz is free software. In order to avoid intellectual property problems with AVM, whose registered trademark "Fritz!" (with exclamation mark) we explicitly acknowledge, we have chosen this deliberately different spelling. The idea for the name came from Alexander Kriegisch (kriegaex), who decided together with Oliver Metz (olistudent) what the project should be called when the version-managed source code repository would be opened to the public. From the (in our opinion daft-sounding) alliteration "Free Fritz" we got "Freetz". ("OpenFritz " was also considered, but we didn't want to ape OpenWrt .) We don't claim that the name is fantastic, but it is short and hopefully easy to remember. :-)

How should I pronounce Freetz?

Like the English word "free" with a German-sounding "tz" on the end, something like "freets".

How did Freetz start?

There are many predecessors to Freetz . A few years ago, Daniel Eiband (danisahne) started the Danisahne-Mod ( DS-Mod ) based on the previous work and cooperation of other creative people (Erik Andersen, Christian Volkmann, Andreas Bühmann, Enrik Berkhan and others). As with Freetz , this allowed and allows modified firmwares to be created, but only for older firmware-versions with Linux kernel 2.4. Since some routers still have firmwares based on the Linux 2.4 kernel, the version ds-0.2.9-p8 is still the current version for some hardware. For the majority of current hardware, the immediate predecessor of Freetz is, however, ds26 (latest version ds26-15.2 ), created by Oliver Metz, which is only suitable for firmware using Linux kernel 2.6. The same applies to Freetz as Freetz is currently nothing other than the current development version of ds26 with a new name. In many files you will therefore still find the name DS-Mod , which will gradually be replaced with the new name Freetz .

Why change the name when DS-Mod has already become well-known?

There are multiple reasons. For one, Daniel has not been actively involved in the development of ds26 for well over a year. For another, he has already started a new project at SourceForge to develop a new DS-Mod from scratch - which we inoffically call DS-Mod NG (Next Generation) - for which the source code repository is publicly available on his project website . We don't wish to take Daniel's project name from him, or to compete with him, but actually hope that he will eventually have more time for his project and that we will be able to combine both versions to have the strengths of both of them in one product. However, at this point in time, the projects have split significantly; DS-Mod NG has a very clean structure, but is not yet finished whereas Freetz (previously ds26 ) is already widely used and is gradually being refactored during the process of development. Where DS-Mod was talked about in recent press coverage (e.g. PC-Welt ), Freetz alias ds26 was meant.

Why is so much of Freetz and the development in German?

AVM is a German company, and their hardware is mainly sold on the German market, where it is very popular and generally the German-language (and German telecoms-system) versions of their products are the first to be released. It is therefore not surprising that the project started in Germany and most of the developers are German. There are some current ideas of how to better integrate internationalization support, and although most development discussions take place in German, contributions in English are most welcome (and will usually be answered in English).


Why change the firmware?

It is possible to edit some special files (character devices) under /var/flash where the contents still exist after reboot, but this is not true for the rest of the filesystem. The content of these character devices is located in its own rather tiny flash partition. Most data is stored on a read-only SquashFS filesystem which can only be modified during a firmware update, using a SquashFS filesystem image. To permanently include (larger) files into the firmware, they must be put into the SqashFS image, which is implemented in Freetz.


Can I get a finished binary of Freetz?

The short answer is no, and this is never likely to be possible. Freetz works by taking the original firmware and applying patches to it. Since the original firmwares contain software which is non-free, as well as some which is free, that means we are not able to distribute finished binary versions. Also, given the number of permutations of modules and hardware then it would be impossible to meet all needs with a limited number of binaries and so it is actually of advantage to have users build their own firmware, tailored to their individual needs.

How can I get Freetz?

See the Getting Started page for how to check out the source code and get started with Freetz . Note that this requires a working Linux installation (a Live-CD or Virtual Machine version will do if you do not want to fully install Linux on your computer). Please make sure that you have basic Linux skills before requesting help as this will make your, and our, lives easier.

Which type of boxes and which firmware versions are currently supported?:

a.) Freetz-1.1.4
b.) freetz-stable-1.1
c.) Trunk


When will version xy be released?

Generally speaking: It's done when it's done. The developers are working in their off time, new releases are provided if the decided-on features are completed and critical bugs were fixed.

Still, a rough plan for new releases does exist: 3-4 months after a stable release we declare a "Feature-Freeze" for the following release. From that time on, only bugs are being fixed. The feature-freeze dates are announced in the roadmap . After the feature-freeze you can expect the final release to be released in about 1 to 1,5 months. Between the stable feature-releases there can be some maintenance-releases provided to support newer firmware versions by AVM or some error-fixes.

Trunk, Branches, Tags?

The trunk is the current development tree. A branch is a tree which is separated from the trunk at a specific time (e.g. r2759 ). Currently the following branches are available: freetz-stable-1.0 and freetz-stable-1.1 . All release versions are tagged (e.g. freetz-1.1.4 )

To check out a stable version:

svn co freetz-stable-1.1

To check out a tag:

svn co freetz-1.1.4

To check out the development version (trunk):

svn co freetz-trunk

Attention! The development version (trunk) is only recommended to novice users with basic Linux knowledge who can troubleshoot elementary errors and can give proper feedback to the developers. Because the trunk is an ongoing development version, it won't be as stable as the branched and tagged versions.

When feature XY is implemented?

The fastest way is to present an working solution. We take notice of every reasonable feature request. Due to the developers designing Freetz in their off time, you have to be patient sometimes.

I like Freetz and I want to support the development.

It is possible to donate money to the development team using the Paypal donation button at the bottom right-hand corner. Further, a specific hardware variation will of course be better supported when the development team has some test hardware. Currently we would very much benefit from some 7270s (who wouldn't?!). There is a thread on the topic of donations at IPPF .

Pre-Configuration (menuconfig)

Do I have the 8MB (v1) or 16MB (v2) version of the FB 7270 ?

1.) read the support file at
2.) The file should contain the following entry:

  • 8MB: flashsize 0x00800000
  • 16MB: flashsize 0x01000000

00800000 Hex = 8.388.608 decimal = 8.192 KB = 8 MB
01000000 Hex = 16.777.216 decimal = 16.384 KB = 16 MB

More details are described [here].

What are indicators for a FB 7270v3 ?

  • the firmware version. Firmwares for the 7270v3 start with 74.xx.xx
  • the serial number

Which packages should be built into a Freetz image ?

We recommend Dropbear? to have SSH access, as well as dnsmasq as DHCP server replacement.

What does "binary only" mean ?

Packages tagged with "binary only" do not supply any web frontend, init script or anything similar. They provide only the binaries themselves, which means you have to take care of the configuration, initialization etc. yourself. (Note: Other than the name (maybe) suggests, these packages are - along with every other package in Freetz - built from source.)

Image Build (make/build)

Meaning of the specific make-targets

A: The make-targets are influencing the build process and creating the firmware. Most of the following information was taken from this thread originally.

1. Clean-Up:

  • make clean
  • make <package>-clean:
    Basically, this calls the clean-target of the original package's Makefile. It will delete all generated files (first and foremost the object-files, libraries and executables) but leaves its configuration intact.
    A following make command doesn't apply changed patches, but creates only the above-named object-files, libraries and executables from the source-files (compiling).
    Example: make mc-clean would clean the "Midnight Commander" package (mc).
  • make <package>-dirclean:
    Deletes the whole directory of the package. A following make command will extract the files, apply the patches, configure and compile the package.
    Only the last stage (compilation) would take place after a make <package>-clean command (as described above).
  • make dirclean:
    As the name implies, this performs a "directory-cleanup". The directories /packages, /source, /build, /toolchain/build, toolchain/target (and some other stuff(?)will be deleted, so that a following make command must build everything new. This is recommended if changes caused by svn up will result in a firmware which is not working as expected. Alternatively, if you know exactly which package(s) are causing them problem, you can clean these package files via make <package>-dirclean individually (see above).
    Note that, after a make dirclean, the build process to create the firmware will take more time than it did before because everything must be rebuilt from scratch.
  • make tools-distclean:
    deletes the tools (busybox, lzma, squashfs, others)
  • make distclean:
    In addition to make dirclean, this also deletes the download folder and the tools.
  • make config-clean-deps:
    If some packages were deselected via make menuconfig, maybe some shared libraries are still selected but are not needed anymore by any active package (that happens because menuconfig cannot recognize this by itself). Such libraries can manually be disabled under 'Advanced Options'→'Shared Libraries' - libaries; the ones that are still in use cannot be deselected. Alternatively, you can also do this automatically via make config-clean-deps. Furthermore, Busybox applets manually selected in make menuconfig will be reset (*not* those modified via make busybox-menuconfig!).
  • make config-clean-deps-keep-busybox:
    Like make config-clean-deps, but does not reset Busybox applets.
  • make kernel-dirclean:
    deletes the current source-tree of the kernel, to build it completely new from clean sources. (important if something has changed at the kernel patches)
  • make kernel-clean:
    analogue to make <package>-clean
  • make kernel-toolchain-dirclean:
    deletes the kernel compiler
  • make target-toolchain-dirclean:
    deletes the compiler for the uClibc and the binaries (executables)

2. Preparations:

  • make world:
    Prerequisite is a toolchain (see Cross-Compiler / Create Toolchain). If problems with non-existing directories occur, it's possible that make world can fix this. But normally this should not be necessary.
  • make kernel-toolchain:
    compiles the kernel and also for the target (Fritzbox)
    Due to historical reasons the label was kept as kernel-toolchain, although, as mentioned, not only the kernel will be built but also the packages (see below).
  • make target-toolchain:
    Compiles the packages for the target (Fritzbox).
  • make kernel-menuconfig:
    The configuration of the kernel will be saved after finishing under ./make/linux/Config.<kernel-ref>.
  • make kernel-precompiled:
    Build the kernel and the kernel modules.
  • make menuconfig (Source): To configure Freetz it makes use of conf/mconf, which some or other already knows from the linux kernel configuration. The ncurses variant mconf can be called with the command make menuconfig.
    By the way:
    A help for each item can be accessed directly in menuconfig by pressing "?".
    After entering "/" you can search across all leaves for any strings - really practical.

Building another firmware language

The firmware language/version should match your box type, else your box will go into a reboot loop.

Check the advanced option Enforce urlader environment and put avm in Patches > Enforce firmware_version variable to build German firmware for an international box. If you want to do this (or the other way around with avme for English firmware on a non-international box), read about recovery and have a working/recovery image ready.

Problems during building

If you encounter problems during the build process, go through this list first:

You must have either have gettext support in your C library, or use the GNU gettext library.

There is a wrong value in config.cache. Delete the file by typing: "rm make/config.cache" or "rm source/target-mipsel_uClibc- 0.X.XX /config.cache"

ERROR: The program/library/header xy was not found…

If the build process was interrupted by this message, some necessary packages for the build system are missing. Please install them and restart the build process.

WARNING: The program/library/header xy was not found…

If the build process was interrupted by this message, maybe some packages providing the needed library are missing. This can be caused by selecting some options or packages in menuconfig. Please install the needed libraries by installing the packages and restart the build process.

No such file `'

This happens every time AVM releases a new firmware version. Normally only the newest file is available on the AVM FTP server. Freetz can only support the version that's current at the release date. Due to license restrictions, we cannot provide these images. Possible solutions (prioritized by difficulty):

  • for everyone: at Firmware-Collector-Thread you can ask for an older firmware version (NO beta firmwares). The image must be downloaded and copied to the directory 'dl/fw'.
  • for beginners: Use the stable Branch from the SVN repository. If possible, update to a newer version which supports the latest AVM firmware versions (or wait for an upcoming Freetz release).
  • for novices: Use the developing tree (trunk) from the SVN repository. The latest firmware versions are supported here.
  • for experts: At make menuconfig? under Advanced Options ⇒ Override firmware source change the name of the file to download and use.

Please use the last 2 possibilities at your own risk. If it's just a "bugfix release" (like the update from .57 to .59) it should work without errors. However, if major changes were done by AVM at the latest firmware release, use it carefully!!

Please copy the following file into the 'dl/fw' sub-directory manually: fritz_box_aa_bb_cc-ddddd.image

The beta firmwares (Labor-Firmware) cannot be downloaded from the AVM-FTP-Server. Please download them manually from the AVM-Labor-Site . You must agree the license terms to get the file. After finishing download, put all files into the 'dl/fw' directory. Please also consider the headpoint before.

./ln: cannot execute binary file

The current working directory '.' is within the path (variable PATH). To make a successfully build, the directory must be removed.

Filesystem image too big

The firmware image doesn't fit into the flash memory of the selected box.

  • With some boxes, this can happen if none of the packages are selected, because the basic Freetz components use some space and the AVM images are just under the maximum flash size. In this case, it's neccessary to use one or more Remove-Patches under the 'Patches'-Section to remove unused components of the original firmware.
  • If a lot packages are selected, reconsider if all packages are really necessary, or try via external/Downloader/USBRoot/NFSRoot to externalize some of the components to reduce the image size. Further information is available at IPPF and in the WIKI
  • With boxes with an USB-Host (e.g. 7170,7270) you can externalize some packages on an USB device (e.g. USB Stick, USB hard disk). The externalize-process is done at the end of the build process via the external-script. At menuconfig, there is an option to do the externalizing. Only predefined parts of packages are being externalized to a USB-Device, as opposed to using USB-Root which will move the entire file system onto the USB drive.
  • If a package was deselected, maybe some shared libraries are still enabled but are not needed anymore. (menuconfig cannot recognize this by itself). These libraries can manually be deselected under 'Advanced Options'→'Shared Libraries' - libraries currently in use cannot be deselected. Another option is to do this via the command make config-clean-deps or make config-clean-deps-keep-busybox, respectively.

WARNING: Not enough free flash space for answering machine!

The image is small enough to fit on flash memory, but you have not enough free space left for the answering machine, or non space left. The firmare should work in spite of this message, but to ensure a fully functional answering machine or fax service, you should use an FAT-formatted USB-Stick to use this space for the answering machine, fax service and other services.

Background Information: Since a few firmware versions, AVM tries to use the remaining bytes in the Flash to create an jffs2-Partition. In this partition all data for e.g. the answering machine, fax service and so on are stored. On older boxes (e.g. 7170) the jffs2-Partition cannot be created as space howsoever is very limited. Please see this message as an warning. More informations at the IPPF-Thread . In FREETZ available since revision r3049 .

The problem still occurs. What now?

At first go into the 'Advanced Options' of menuconfig, change the 'Verbosity Level' to 2 and execute make again. After that go to the IPPF Forum and search for the error message or for an existing thread. If nothing could be found, create a new thread to get help with the given error message (please post it inside Code-Tags), the file .config (your configuration as attachment) and the used version or SVN branch/-revision.

Flashing of Compiled Image

Problems after (successful) Flashing

Settings are not available at current security level

There are several security levels. The level can be changed using the following commands:

   echo x > /tmp/flash/security ( after r3318: echo x > /tmp/flash/mod/security)

 * with x being one of the following values:
 * 0 : no restrictions
 * 1 : only configuration files without shell commands (shell scripts) can be modified
 * 2 : no configuration files can be modified

What is the default password for freetz?

The default password for freetz (both for console and web login) is "freetz". Login name for console is "root", and for the web interface it is admin. When you first log in using telnet or ssh, you have to change your password.

The info led blinks twice periodically

See this thread.


Were is the whole configuration stored on the Fritzbox ?

The whole configuration on the Fritzbox can be found under /tmp/flash. This is important if you build a Freetz firmware, because the configuration is not located in the static firmware part of the image. All files located under /tmp/flash were not be edited during a firmware update, so the configuration files will be keeped after a firmware update. Important, always execute "modsave" after making changes on the configuration files under /tmp/flash, to save them in the flash. More information about that see below.

Configuration not available at the current security level!

There are different security levels. Depending on the selected level, not all configuration files are editable.

echo x > /tmp/flash/security (since r3318: echo x > /tmp/flash/mod/security)
# with x being one of the following values:
# 0 : no restrictions
# 1 : only configuration files without shell commands (shell scripts) can be modified
# 2 : no configuration files can be modified

/!\ ATTENTION: Between x and > there must be at least a single blank space. If there isn't, the file will be empty. (echo will redirect to stdout. The output would be empty then. Alternatively, you could also write "x">security.

This must be done after installing the new firmware on the Box via Telnet or SSH (not possible over the Rudi-Shell, because it also requires security level "0").

How can i disable the password for the Freetz-Website?

Execute the following command on the terminal:

touch /tmp/flash/webcfg_conf
chmod +x /tmp/flash/webcfg_conf
modsave flash
/etc/init.d/rc.webcfg restart

Background: The script /tmp/flash/webcfg_conf will be preferred compared to /etc/default.webcfg/webcfg_conf to create the configuration file. An empty script /tmp/flash/webcfg_conf will create an empty configuration file without a password.

/!\ For Freetz-1.1.x replace /tmp/flash/webcfg_conf with /tmp/flash/httpd_conf .

How can i change the password for the Freetz-Website?

This can be done via the web interface by itself:

How can i reset the password for the Freetz-Website in case I've lost it but still have access via telnet/SSH ?

At first, stop the Freetz-Webif:

/etc/init.d/rc.webcfg stop

Then use vi to open the file mod.cfg and edit the line that begins with "export MOD_HTTPD_PASSWD" as follows:

vi /var/mod/etc/conf/mod.cfg
export MOD_HTTPD_PASSWD='$1$$zO6d3zi9DefdWLMB.OHaO.'

Now start the Freetz-Web interface:

/etc/init.d/rc.webcfg start

Now you can log in to the Web interface with the password "freetz".

Please consider, that this change will NOT persist across reboots. So after a reboot, you still have the old unknown password.
Therefore, you should change the password of the Box in the freetz-menu under Settings before you reboot your Fritzbox.

How can I change the root-Password?

Execute the following commands on the terminal:

modusers save
modsave flash

After entering 'passwd' you must type in the password. While typing, the password will 'not' be shown. Too simple passwords will not be accepted.

Problems During Working

/var/flash/freetz too big

The default limit set by Freetz for the maximum size of the configuration was exceeded. This limit is a protection to prevent an unintended full TFFS. This limit can be increased, but you should keep an eye on the current fill level:

modconf set mod MOD_LIMIT=<bytes>
modconf save mod
modsave flash

/!\ As of r5706 the setting MOD_LIMIT is obsolete.

No ftp access after Freetz

This is a problem which occurs especially in Freetz 1.1.x. More details and solution can be found in the howto .

Removing FREETZ and Other Modifications


How can I use an own/other DNS server for all connected PCs and Fritzbox ?

AVM doesn't allow the modification of the default DNS servers the Box is using, instead of other routers which can change it via the WebUI. (End of 2009).

Possible Solutions:

  • dnsmasq: Installation of an own DNS server on the Fritzbox with the package dnsmasq. This is a general possibility which is working on every box. This requires a modification (freetzing) of the firmware image. With an edited version of /etc/resolv.conf (if using the trunk version, this is possible via the GUI under "Settings"→"Freetz: resolv.conf") you can add a DNS server: "nameserver" (example with the OpenDNS server)
  • without dnsmasq: At some boxes, e.g. 7170(FV 29.04.76) it's possible to edit the central config file of AVM. With the command "nvi /var/flash/ar7.cfg" all entries of "overwrite_dns1 =" and "overwrite_dns2 =" must be edited. It's recommended that only persons with basic knowledge of nvi and telnet respectivly ssh/telnet should do that! Here, the multid from AVM is running as DNS server. At the resolv.conf a loopback entry "nameserver" exists. This is allowing Linux standard applications the resolving at the Fritzbox over the multid.
  • Editing the /etc/resolv.conf: If its only about changing the current used DNS of the Fritzbox, editing /etc/resolv.conf like described above at dnsmasq also works. This is only affecting the name resolution of the Box, connected clients are still using the standard DNS.

How can I create character devices ?

Freetz uses also a character device, which can save files enduring with help of a Tiny Flash Filesystems (TFFS) in the Flash, to save the configuration. Prerequisite is a minor number, which is not used by any other character device under /var/flash/ (Freetz uses the minor 0x3c), the major number can be read from /proc/devices:

mknod /var/flash/<name-of-file> c <major> <minor>

Because this character device is created in a ramdisk under /var/, this command must be executed every time during a restart. The content is achieving (?). /!\ To edit such character devices never use vi! For this case, there is the wrapper script nvi.

/!\ ATTENTION: The flash partition of the TFFS is very small and not capable to contain files > 10-30 KB (depending on the size of the other files).

The current fill level can be shown like this:

echo 'cleanup' > /proc/tffs

echo 'info' > /proc/tffs

cat /proc/tffs | grep '^fill='

Which network cable is necessary for a recover ?

RJ45 standard network cable, no crossover

How old is my FritzBox ?

The first four characters of the box' serial number describe its age:

Example: W484-xxx-xx-xxx-xxx ⇒ Thursday, 27.11.2008

U = 2006
V = 2007
W = 2008
X = 2009
A = 2010

W451 = calendar week 45 and the first day of that week = Monday
W462 = calendar week 46 and the second day of that week = Tuesday
W473 = calendar week 47 and the third day of that week = Wednesday
W484 = calendar week 48 and the fourth day of that week = Thursday
W495 = calendar week 49 the fifth day of that week = Friday

How much RAM does my FritzBox contain?

For the second xxxx-XXX-xxx-xxx currently, the following codes are known to occur:

Example: W484-305-xx-xxx-xxx ⇒ Fritzbox with 16MB and 1und1 branding

293 - HWRev 122 (8MB/7270_V1) - AVM branding
294 - HWRev 122 (8MB/7270_V1) - 1und1 branding
304 - HWRev 139 (16MB/7270_V2) - AVM branding
305 - HWRev 139 (16MB/7270_V2) - 1und1 branding
xxx - HWRev 145 (16MB/7270_V3) - ??? branding - 7270_V3
307 - HWRev 139 (16MB/7270_V2) - AVME branding International Version?
310 - HWRev 139 (16MB/7270_V2) - AVME branding A-/CH-Version?