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diff --git a/doc/bird.sgml b/doc/bird.sgml index 31b2c03..01e70e8 100644 --- a/doc/bird.sgml +++ b/doc/bird.sgml @@ -145,10 +145,42 @@ options. The most important ones are: <tag>-s <m/name of communication socket/</tag> use given filename for a socket for communications with the client, default is <it/prefix/<file>/var/run/bird.ctl</file>. + + <tag>-u <m/user/</tag> + drop privileges and use that user ID, see the next section for details. + + <tag>-g <m/group/</tag> + use that group ID, see the next section for details. </descrip> <p>BIRD writes messages about its work to log files or syslog (according to config). +<sect>Privileges + +<p>BIRD, as a routing daemon, uses several privileged operations (like +setting routing table and using raw sockets). Traditionally, BIRD is +executed and runs with root privileges, which may be prone to security +problems. The recommended way is to use a privilege restriction +(options <cf/-u/, <cf/-g/). In that case BIRD is executed with root +privileges, but it changes its user and group ID to an unprivileged +ones, while using Linux capabilities to retain just required +privileges (capabilities CAP_NET_*). Note that the control socket is +created before the privileges are dropped, but the config file is read +after that. The privilege restriction is not implemented in BSD port +of BIRD. + +<p>A nonprivileged user (as an argument to <cf/-u/ options) may be the +user <cf/nobody/, but it is suggested to use a new dedicated user +account (like <cf/bird/). The similar considerations apply for +the group option, but there is one more condition -- the users +in the same group can use <file/birdc/ to control BIRD. + +<p>Finally, there is a possibility to use external tools to run BIRD in +an environment with restricted privileges. This may need some +configuration, but it is generally easy -- BIRD needs just the +standard library, privileges to read the config file and create the +control socket and the CAP_NET_* capabilities. + <chapt>About routing tables <p>BIRD has one or more routing tables which may or may not be |