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man:gai

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

NAME

     gai.conf - getaddrinfo(3) configuration file

DESCRIPTION

     A  call  to getaddrinfo(3) might return multiple answers.  According to
     RFC 3484 these answers must be sorted so that the answer with the high-
     est  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 sort-
            ing.   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  con-
            figuration  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  neces-
            sary.

FILES

     /etc/gai.conf

VERSIONS

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

EXAMPLE

     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 prece-
         dence ::/96          20 precedence ::ffff:0:0/96  10

SEE ALSO

     getaddrinfo(3), RFC 3484

COLOPHON

     This  page  is  part of release 4.16 of the Linux man-pages project.  A
     description of the project, information about reporting bugs,  and  the
     latest     version     of     this    page,    can    be    found    at
     https://www.kernel.org/doc/man-pages/.

Linux 2016-03-15 GAI.CONF(5)

/data/webs/external/dokuwiki/data/pages/man/gai.txt · Last modified: 2019/05/17 09:47 by 127.0.0.1

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