doc/user/vtysh.rst

   1 .. _vty-shell:
   2
   3 *********
   4 VTY shell
   5 *********
   6
   7 .. program:: configure
   8
   9 *vtysh* provides a combined frontend to all FRR daemons in a single combined
  10 session. It is enabled by default at build time, but can be disabled through
  11 the :option:`--disable-vtysh` option to the configure script.
  12
  13 *vtysh* has a configuration file, :file:`vtysh.conf`. The location of that
  14 file cannot be changed from |INSTALL_PREFIX_ETC| since it contains options
  15 controlling authentication behavior. This file will also not be written by
  16 configuration-save commands, it is intended to be updated manually by an
  17 administrator with an external editor.
  18
  19 .. warning::
  20
  21    This also means the ``hostname`` and ``banner motd`` commands (which both do
  22    have effect for vtysh) need to be manually updated in :file:`vtysh.conf`.
  23
  24
  25 Pager usage
  26 ===========
  27
  28 *vtysh* can call an external paging program (e.g. *more* or *less*) to
  29 paginate long output from commands.  This feature used to be enabled by
  30 default but is now controlled by the ``VTYSH_PAGER`` environment variable
  31 and the :clicmd:`terminal paginate` command:
  32
  33 .. envvar:: VTYSH_PAGER
  34
  35    If set, the ``VTYSH_PAGER`` environment variable causes *vtysh* to pipe
  36    output from commands through the given command.  Note that this happens
  37    regardless of the length of the output.  As such, standard pager behavior
  38    (particularly waiting at the end of output) tends to be annoying to the
  39    user.  Using ``less -EFX`` is recommended for a better user experience.
  40
  41    If this environment variable is unset, *vtysh* defaults to not using any
  42    pager.
  43
  44    This variable should be set by the user according to their preferences,
  45    in their :file:`~/.profile` file.
  46
  47 .. index:: [no] terminal paginate
  48 .. clicmd:: [no] terminal paginate
  49
  50    Enables/disables vtysh output pagination.  This command is intended to
  51    be placed in :file:`vtysh.conf` to set a system-wide default.  If this
  52    is enabled but ``VTYSH_PAGER`` is not set, the system default pager
  53    (likely ``more`` or ``/usr/bin/pager``) will be used.
  54
  55
  56 Permissions and setup requirements
  57 ==================================
  58
  59 *vtysh* connects to running daemons through Unix sockets located in
  60 |INSTALL_PREFIX_STATE|. Running vtysh thus requires access to that directory,
  61 plus membership in the |INSTALL_VTY_GROUP| group (which is the group that the
  62 daemons will change ownership of their sockets to).
  63
  64 To restrict access to FRR configuration, make sure no unauthorized users are
  65 members of the |INSTALL_VTY_GROUP| group.
  66
  67 .. warning::
  68
  69    VTYSH implements a CLI option ``-u, --user`` that disallows entering the
  70    characters "en" on the command line, which ideally restricts access to
  71    configuration commands. However, VTYSH was never designed to be a privilege
  72    broker and is not built using secure coding practices. No guarantees of
  73    security are provided for this option and under no circumstances should this
  74    option be used to provide any semblance of security or read-only access to
  75    FRR.
  76
  77 PAM support (experimental)
  78 --------------------------
  79
  80 vtysh has working (but rather useless) PAM support. It will perform an
  81 "authenticate" PAM call using |PACKAGE_NAME| as service name. No other
  82 (accounting, session, password change) calls will be performed by vtysh.
  83
  84 Users using vtysh still need to have appropriate access to the daemons' VTY
  85 sockets, usually by being member of the |INSTALL_VTY_GROUP| group. If they
  86 have this membership, PAM support is useless since they can connect to daemons
  87 and issue commands using some other tool. Alternatively, the *vtysh* binary
  88 could be made SGID (set group ID) to the |INSTALL_VTY_GROUP| group.
  89
  90 .. warning::
  91
  92    No security guarantees are made for this configuration.
  93
  94
  95 .. index:: username USERNAME nopassword
  96 .. clicmd:: username USERNAME nopassword
  97
  98   If PAM support is enabled at build-time, this command allows disabling the
  99   use of PAM on a per-user basis. If vtysh finds that an user is trying to
 100   use vtysh and a "nopassword" entry is found, no calls to PAM will be made
 101   at all.
 102
 103
 104 .. _integrated-configuration-mode:
 105
 106 Integrated configuration mode
 107 =============================
 108
 109 Integrated configuration mode uses a single configuration file,
 110 :file:`frr.conf`, for all daemons. This replaces the individual files like
 111 :file:`zebra.conf` or :file:`bgpd.conf`.
 112
 113 :file:`frr.conf` is located in |INSTALL_PREFIX_ETC|. All daemons check for the
 114 existence of this file at startup, and if it exists will not load their
 115 individual configuration files. Instead, ``vtysh -b`` must be invoked to
 116 process :file:`frr.conf` and apply its settings to the individual daemons.
 117
 118 .. warning::
 119
 120    *vtysh -b* must also be executed after restarting any daemon.
 121
 122
 123 Configuration saving, file ownership and permissions
 124 ----------------------------------------------------
 125
 126 The :file:`frr.conf` file is not written by any of the daemons; instead *vtysh*
 127 contains the necessary logic to collect configuration from all of the daemons,
 128 combine it and write it out.
 129
 130 .. warning::
 131
 132    Daemons must be running for *vtysh* to be able to collect their
 133    configuration. Any configuration from non-running daemons is permanently
 134    lost after doing a configuration save.
 135
 136 Since the *vtysh* command may be running as ordinary user on the system,
 137 configuration writes will be tried through *watchfrr*, using the ``write
 138 integrated`` command internally. Since *watchfrr* is running as superuser,
 139 *vtysh* is able to ensure correct ownership and permissions on
 140 :file:`frr.conf`.
 141
 142 If *watchfrr* is not running or the configuration write fails, *vtysh* will
 143 attempt to directly write to the file. This is likely to fail if running as
 144 unprivileged user; alternatively it may leave the file with incorrect owner or
 145 permissions.
 146
 147 Writing the configuration can be triggered directly by invoking *vtysh -w*.
 148 This may be useful for scripting. Note this command should be run as either the
 149 superuser or the FRR user.
 150
 151 We recommend you do not mix the use of the two types of files. Further, it is
 152 better not to use the integrated :file:`frr.conf` file, as any syntax error in
 153 it can lead to /all/ of your daemons being unable to start up. Per daemon files
 154 are more robust as impact of errors in configuration are limited to the daemon
 155 in whose file the error is made.
 156
 157 .. index:: service integrated-vtysh-config
 158 .. clicmd:: service integrated-vtysh-config
 159
 160 .. index:: no service integrated-vtysh-config
 161 .. clicmd:: no service integrated-vtysh-config
 162
 163    Control whether integrated :file:`frr.conf` file is written when
 164    'write file' is issued.
 165
 166    These commands need to be placed in :file:`vtysh.conf` to have any effect.
 167    Note that since :file:`vtysh.conf` is not written by FRR itself, they
 168    therefore need to be manually placed in that file.
 169
 170    This command has 3 states:
 171
 172
 173    service integrated-vtysh-config
 174       *vtysh* will always write :file:`frr.conf`.
 175
 176
 177    no service integrated-vtysh-config
 178       *vtysh* will never write :file:`frr.conf`; instead it will ask
 179       daemons to write their individual configuration files.
 180
 181    Neither option present (default)
 182       *vtysh* will check whether :file:`frr.conf` exists. If it does,
 183       configuration writes will update that file. Otherwise, writes are performed
 184       through the individual daemons.
 185
 186    This command is primarily intended for packaging/distribution purposes, to
 187    preset one of the two operating modes and ensure consistent operation across
 188    installations.
 189
 190 .. index:: write integrated
 191 .. clicmd:: write integrated
 192
 193    Unconditionally (regardless of ``service integrated-vtysh-config`` setting)
 194    write out integrated :file:`frr.conf` file through *watchfrr*. If *watchfrr*
 195    is not running, this command is unavailable.
 196
 197 .. warning::
 198
 199    Configuration changes made while some daemon is not running will be
 200    invisible to that daemon. The daemon will start up with its saved
 201    configuration (either in its individual configuration file, or in
 202    :file:`frr.conf`).  This is particularly troublesome for route-maps and
 203    prefix lists, which would otherwise be synchronized between daemons.
 204