Knowledge Base ISC Main Website Ask a Question/Contact ISC
Why am I seeing this message: 'named' uses 32-bit capabilities (legacy support in use) ?
Author: ISC Support Reference Number: AA-00823 Views: 13904 Created: 2012-10-26 18:58 Last Updated: 2017-10-25 15:34 0 Rating/ Voters

When building BIND to run in a 64-bit environment, the following message may be logged by the kernel when starting BIND:

warning:`named' uses 32-bit capabilities (legacy support in use)

This does not mean that BIND has not been built as a 64-bit binary.  You can confirm that the binary is a 64-bit executable using the file command, for example:

$ file /dns/sbin/named
/dns/sbin/named: ELF 64-bit LSB executable, x86-64, version 1 (SYSV),
dynamically linked (uses shared libs), for GNU/Linux 2.6.18, not

This warning can be safely ignored, although most administrators will want to resolve the underlying problem being highlighted - which is either that named is not using libcap at all, or that it is using the 32-bit libcap library. It is the libcap2 package that provides full 64-bit support.  BIND needs to be built with libcap2 to resolve the warning. 

Therefore you should:

  • Install libcap2
  • In the BIND source code directory, remove the results of the previous configure step:
    $ make clean
  • Run configure again, with your usual options and settings, and then also check that BIND has detected capability.h and will build using libcap by searching config.h for HAVE_LIBCAP 1.  (Note that capability.h is provided by both libcap and libcap2).

    $ grep LIBCAP config.h
    #define HAVE_LIBCAP 1

  • Then complete the build and install of BIND.

BIND needs the libcap2 header files to be available during the configure step in order to use libcap2

Although you may have the libcap2 package installed, on many linux variants, particularly debian, header files for an application library are delivered separately with the application-dev package, so unless this is also installed, software builds that depend on the header files won't be able to make use of it.  Therefore, you may also need to install libcap2-dev prior to building BIND.

Some linux distributions may make the libcap2 header files available as a package named libcap-dev

You may find that there is no package available named libcap2-dev for your distribution.  In that case, we suggest that you check the details of the libcap-dev package instead to see if that provides what you need.

© 2001-2018 Internet Systems Consortium

For assistance with problems and questions for which you have not been able to find an answer in our Knowledge Base, we recommend searching our community mailing list archives and/or posting your question there (you will need to register there first for your posts to be accepted). The bind-users and the dhcp-users lists particularly have a long-standing and active membership.

ISC relies on the financial support of the community to fund the development of its open source software products. If you would like to support future product evolution and maintenance as well having peace of mind knowing that our team of experts are poised to provide you with individual technical assistance whenever you call upon them, then please consider our Professional Subscription Support services - details can be found on our main website.

  • There is no feedback for this article
Quick Jump Menu