gai.conf(5) — Linux manual page

NAME | DESCRIPTION | FILES | VERSIONS | EXAMPLES | SEE ALSO | COLOPHON

GAI.CONF(5)             Linux Programmer's Manual            GAI.CONF(5)

NAME         top

       gai.conf - getaddrinfo(3) configuration file

DESCRIPTION         top

       A call to getaddrinfo(3) might return multiple answers.
       According to RFC 3484 these answers must be sorted so that the
       answer with the highest success rate is first in the list.  The
       RFC provides an algorithm for the sorting.  The static rules are
       not always adequate, though.  For this reason, the RFC also
       requires that system administrators should have the possibility
       to dynamically change the sorting.  For the glibc implementation,
       this can be achieved with the /etc/gai.conf file.

       Each line in the configuration file consists of a keyword and its
       parameters.  White spaces in any place are ignored.  Lines
       starting with '#' are comments and are ignored.

       The keywords currently recognized are:

       label netmask precedence
              The value is added to the label table used in the RFC 3484
              sorting.  If any label definition is present in the
              configuration file, the default table is not used.  All
              the label definitions of the default table which are to be
              maintained have to be duplicated.  Following the keyword,
              the line has to contain a network mask and a precedence
              value.

       precedence netmask precedence
              This keyword is similar to label, but instead the value is
              added to the precedence table as specified in RFC 3484.
              Once again, the presence of a single precedence line in
              the configuration file causes the default table to not be
              used.

       reload <yes|no>
              This keyword controls whether a process checks whether the
              configuration file has been changed since the last time it
              was read.  If the value is "yes", the file is reread.
              This might cause problems in multithreaded applications
              and is generally a bad idea.  The default is "no".

       scopev4 mask value
              Add another rule to the RFC 3484 scope table for IPv4
              address.  By default, the scope IDs described in section
              3.2 in RFC 3438 are used.  Changing these defaults should
              hardly ever be necessary.

FILES         top

       /etc/gai.conf

VERSIONS         top

       The gai.conf file is supported by glibc since version 2.5.

EXAMPLES         top

       The default table according to RFC 3484 would be specified with
       the following configuration file:

           label  ::1/128       0
           label  ::/0          1
           label  2002::/16     2
           label ::/96          3
           label ::ffff:0:0/96  4
           precedence  ::1/128       50
           precedence  ::/0          40
           precedence  2002::/16     30
           precedence ::/96          20
           precedence ::ffff:0:0/96  10

SEE ALSO         top

       getaddrinfo(3), RFC 3484

COLOPHON         top

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Linux                          2020-06-09                    GAI.CONF(5)

Pages that refer to this page: pmdanetcheck(1)getaddrinfo(3)