Adding upstream version 8.4.4.upstream/8.4.4upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 225 insertions, 0 deletions

diff --git a/doc/user/vtysh.rst b/doc/user/vtysh.rst
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+.. _vty-shell:
+
+*********
+VTY shell
+*********
+
+.. program:: configure
+
+*vtysh* provides a combined frontend to all FRR daemons in a single combined
+session. It is enabled by default at build time, but can be disabled through
+the :option:`--disable-vtysh` option to the configure script.
+
+*vtysh* has a configuration file, :file:`vtysh.conf`. The location of that
+file cannot be changed from |INSTALL_PREFIX_ETC| since it contains options
+controlling authentication behavior. This file will also not be written by
+configuration-save commands, it is intended to be updated manually by an
+administrator with an external editor.
+
+.. warning::
+
+   This also means the ``hostname`` and ``banner motd`` commands (which both do
+   have effect for vtysh) need to be manually updated in :file:`vtysh.conf`.
+
+
+.. clicmd:: copy FILENAME running-config
+
+   Process and load a configuration file manually; each line in the
+   file is read and processed as if it were being typed (or piped) to
+   vtysh.
+
+
+Live logs
+=========
+
+.. clicmd:: terminal monitor [DAEMON]
+
+   Receive and display log messages.
+
+   It is not currently possible to change the minimum message priority (fixed
+   to debug) or output formatting.  These will likely be made configurable in
+   the future.
+
+   Log messages are received asynchronously and may be printed both during
+   command execution as well as while on the prompt.  They are printed to
+   stderr, unlike regular CLI output which is printed to stdout.  The intent is
+   that stdin/stdout might be driven by some script while log messages are
+   visible on stderr.  If stdout and stderr are the same file, the prompt and
+   pending input will be cleared and reprinted appropriately.
+
+   .. note::
+
+      If ``vtysh`` cannot keep up, some log messages may be lost.  The daemons
+      do **not** wait for, get blocked by, or buffer messages for ``vtysh``.
+
+
+Pager usage
+===========
+
+*vtysh* can call an external paging program (e.g. *more* or *less*) to
+paginate long output from commands.  This feature used to be enabled by
+default but is now controlled by the ``VTYSH_PAGER`` environment variable
+and the :clicmd:`terminal paginate` command:
+
+.. envvar:: VTYSH_PAGER
+
+   If set, the ``VTYSH_PAGER`` environment variable causes *vtysh* to pipe
+   output from commands through the given command.  Note that this happens
+   regardless of the length of the output.  As such, standard pager behavior
+   (particularly waiting at the end of output) tends to be annoying to the
+   user.  Using ``less -EFX`` is recommended for a better user experience.
+
+   If this environment variable is unset, *vtysh* defaults to not using any
+   pager.
+
+   This variable should be set by the user according to their preferences,
+   in their :file:`~/.profile` file.
+
+.. clicmd:: terminal paginate
+
+   Enables/disables vtysh output pagination.  This command is intended to
+   be placed in :file:`vtysh.conf` to set a system-wide default.  If this
+   is enabled but ``VTYSH_PAGER`` is not set, the system default pager
+   (likely ``more`` or ``/usr/bin/pager``) will be used.
+
+
+Permissions and setup requirements
+==================================
+
+*vtysh* connects to running daemons through Unix sockets located in
+|INSTALL_PREFIX_STATE|. Running vtysh thus requires access to that directory,
+plus membership in the |INSTALL_VTY_GROUP| group (which is the group that the
+daemons will change ownership of their sockets to).
+
+To restrict access to FRR configuration, make sure no unauthorized users are
+members of the |INSTALL_VTY_GROUP| group.
+
+.. warning::
+
+   VTYSH implements a CLI option ``-u, --user`` that disallows entering the
+   characters "en" on the command line, which ideally restricts access to
+   configuration commands. However, VTYSH was never designed to be a privilege
+   broker and is not built using secure coding practices. No guarantees of
+   security are provided for this option and under no circumstances should this
+   option be used to provide any semblance of security or read-only access to
+   FRR.
+
+PAM support (experimental)
+--------------------------
+
+vtysh has working (but rather useless) PAM support. It will perform an
+"authenticate" PAM call using |PACKAGE_NAME| as service name. No other
+(accounting, session, password change) calls will be performed by vtysh.
+
+Users using vtysh still need to have appropriate access to the daemons' VTY
+sockets, usually by being member of the |INSTALL_VTY_GROUP| group. If they
+have this membership, PAM support is useless since they can connect to daemons
+and issue commands using some other tool. Alternatively, the *vtysh* binary
+could be made SGID (set group ID) to the |INSTALL_VTY_GROUP| group.
+
+.. warning::
+
+   No security guarantees are made for this configuration.
+
+
+.. clicmd:: username USERNAME nopassword
+
+  If PAM support is enabled at build-time, this command allows disabling the
+  use of PAM on a per-user basis. If vtysh finds that an user is trying to
+  use vtysh and a "nopassword" entry is found, no calls to PAM will be made
+  at all.
+
+
+.. _integrated-configuration-mode:
+
+Integrated configuration mode
+=============================
+
+Integrated configuration mode uses a single configuration file,
+:file:`frr.conf`, for all daemons. This replaces the individual files like
+:file:`zebra.conf` or :file:`bgpd.conf`.
+
+:file:`frr.conf` is located in |INSTALL_PREFIX_ETC|. All daemons check for the
+existence of this file at startup, and if it exists will not load their
+individual configuration files. Instead, ``vtysh -b`` must be invoked to
+process :file:`frr.conf` and apply its settings to the individual daemons.
+
+.. warning::
+
+   *vtysh -b* must also be executed after restarting any daemon.
+
+
+Configuration saving, file ownership and permissions
+----------------------------------------------------
+
+The :file:`frr.conf` file is not written by any of the daemons; instead *vtysh*
+contains the necessary logic to collect configuration from all of the daemons,
+combine it and write it out.
+
+.. warning::
+
+   Daemons must be running for *vtysh* to be able to collect their
+   configuration. Any configuration from non-running daemons is permanently
+   lost after doing a configuration save.
+
+Since the *vtysh* command may be running as ordinary user on the system,
+configuration writes will be tried through *watchfrr*, using the ``write
+integrated`` command internally. Since *watchfrr* is running as superuser,
+*vtysh* is able to ensure correct ownership and permissions on
+:file:`frr.conf`.
+
+If *watchfrr* is not running or the configuration write fails, *vtysh* will
+attempt to directly write to the file. This is likely to fail if running as
+unprivileged user; alternatively it may leave the file with incorrect owner or
+permissions.
+
+Writing the configuration can be triggered directly by invoking *vtysh -w*.
+This may be useful for scripting. Note this command should be run as either the
+superuser or the FRR user.
+
+We recommend you do not mix the use of the two types of files.
+
+.. clicmd:: service integrated-vtysh-config
+
+
+   Control whether integrated :file:`frr.conf` file is written when
+   'write file' is issued.
+
+   These commands need to be placed in :file:`vtysh.conf` to have any effect.
+   Note that since :file:`vtysh.conf` is not written by FRR itself, they
+   therefore need to be manually placed in that file.
+
+   This command has 3 states:
+
+
+   service integrated-vtysh-config
+      *vtysh* will always write :file:`frr.conf`.
+
+
+   no service integrated-vtysh-config
+      *vtysh* will never write :file:`frr.conf`; instead it will ask
+      daemons to write their individual configuration files.
+
+   Neither option present (default)
+      *vtysh* will check whether :file:`frr.conf` exists. If it does,
+      configuration writes will update that file. Otherwise, writes are performed
+      through the individual daemons.
+
+   This command is primarily intended for packaging/distribution purposes, to
+   preset one of the two operating modes and ensure consistent operation across
+   installations.
+
+.. clicmd:: write integrated
+
+   Unconditionally (regardless of ``service integrated-vtysh-config`` setting)
+   write out integrated :file:`frr.conf` file through *watchfrr*. If *watchfrr*
+   is not running, this command is unavailable.
+
+.. warning::
+
+   Configuration changes made while some daemon is not running will be
+   invisible to that daemon. The daemon will start up with its saved
+   configuration (either in its individual configuration file, or in
+   :file:`frr.conf`).  This is particularly troublesome for route-maps and
+   prefix lists, which would otherwise be synchronized between daemons.
+