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 .. clicmd:: copy FILENAME running-config
  26
  27    Process and load a configuration file manually; each line in the
  28    file is read and processed as if it were being typed (or piped) to
  29    vtysh.
  30
  31
  32 Pager usage
  33 ===========
  34
  35 *vtysh* can call an external paging program (e.g. *more* or *less*) to
  36 paginate long output from commands.  This feature used to be enabled by
  37 default but is now controlled by the ``VTYSH_PAGER`` environment variable
  38 and the :clicmd:`terminal paginate` command:
  39
  40 .. envvar:: VTYSH_PAGER
  41
  42    If set, the ``VTYSH_PAGER`` environment variable causes *vtysh* to pipe
  43    output from commands through the given command.  Note that this happens
  44    regardless of the length of the output.  As such, standard pager behavior
  45    (particularly waiting at the end of output) tends to be annoying to the
  46    user.  Using ``less -EFX`` is recommended for a better user experience.
  47
  48    If this environment variable is unset, *vtysh* defaults to not using any
  49    pager.
  50
  51    This variable should be set by the user according to their preferences,
  52    in their :file:`~/.profile` file.
  53
  54 .. clicmd:: terminal paginate
  55
  56    Enables/disables vtysh output pagination.  This command is intended to
  57    be placed in :file:`vtysh.conf` to set a system-wide default.  If this
  58    is enabled but ``VTYSH_PAGER`` is not set, the system default pager
  59    (likely ``more`` or ``/usr/bin/pager``) will be used.
  60
  61
  62 Permissions and setup requirements
  63 ==================================
  64
  65 *vtysh* connects to running daemons through Unix sockets located in
  66 |INSTALL_PREFIX_STATE|. Running vtysh thus requires access to that directory,
  67 plus membership in the |INSTALL_VTY_GROUP| group (which is the group that the
  68 daemons will change ownership of their sockets to).
  69
  70 To restrict access to FRR configuration, make sure no unauthorized users are
  71 members of the |INSTALL_VTY_GROUP| group.
  72
  73 .. warning::
  74
  75    VTYSH implements a CLI option ``-u, --user`` that disallows entering the
  76    characters "en" on the command line, which ideally restricts access to
  77    configuration commands. However, VTYSH was never designed to be a privilege
  78    broker and is not built using secure coding practices. No guarantees of
  79    security are provided for this option and under no circumstances should this
  80    option be used to provide any semblance of security or read-only access to
  81    FRR.
  82
  83 PAM support (experimental)
  84 --------------------------
  85
  86 vtysh has working (but rather useless) PAM support. It will perform an
  87 "authenticate" PAM call using |PACKAGE_NAME| as service name. No other
  88 (accounting, session, password change) calls will be performed by vtysh.
  89
  90 Users using vtysh still need to have appropriate access to the daemons' VTY
  91 sockets, usually by being member of the |INSTALL_VTY_GROUP| group. If they
  92 have this membership, PAM support is useless since they can connect to daemons
  93 and issue commands using some other tool. Alternatively, the *vtysh* binary
  94 could be made SGID (set group ID) to the |INSTALL_VTY_GROUP| group.
  95
  96 .. warning::
  97
  98    No security guarantees are made for this configuration.
  99
 100
 101 .. clicmd:: username USERNAME nopassword
 102
 103   If PAM support is enabled at build-time, this command allows disabling the
 104   use of PAM on a per-user basis. If vtysh finds that an user is trying to
 105   use vtysh and a "nopassword" entry is found, no calls to PAM will be made
 106   at all.
 107
 108
 109 .. _integrated-configuration-mode:
 110
 111 Integrated configuration mode
 112 =============================
 113
 114 Integrated configuration mode uses a single configuration file,
 115 :file:`frr.conf`, for all daemons. This replaces the individual files like
 116 :file:`zebra.conf` or :file:`bgpd.conf`.
 117
 118 :file:`frr.conf` is located in |INSTALL_PREFIX_ETC|. All daemons check for the
 119 existence of this file at startup, and if it exists will not load their
 120 individual configuration files. Instead, ``vtysh -b`` must be invoked to
 121 process :file:`frr.conf` and apply its settings to the individual daemons.
 122
 123 .. warning::
 124
 125    *vtysh -b* must also be executed after restarting any daemon.
 126
 127
 128 Configuration saving, file ownership and permissions
 129 ----------------------------------------------------
 130
 131 The :file:`frr.conf` file is not written by any of the daemons; instead *vtysh*
 132 contains the necessary logic to collect configuration from all of the daemons,
 133 combine it and write it out.
 134
 135 .. warning::
 136
 137    Daemons must be running for *vtysh* to be able to collect their
 138    configuration. Any configuration from non-running daemons is permanently
 139    lost after doing a configuration save.
 140
 141 Since the *vtysh* command may be running as ordinary user on the system,
 142 configuration writes will be tried through *watchfrr*, using the ``write
 143 integrated`` command internally. Since *watchfrr* is running as superuser,
 144 *vtysh* is able to ensure correct ownership and permissions on
 145 :file:`frr.conf`.
 146
 147 If *watchfrr* is not running or the configuration write fails, *vtysh* will
 148 attempt to directly write to the file. This is likely to fail if running as
 149 unprivileged user; alternatively it may leave the file with incorrect owner or
 150 permissions.
 151
 152 Writing the configuration can be triggered directly by invoking *vtysh -w*.
 153 This may be useful for scripting. Note this command should be run as either the
 154 superuser or the FRR user.
 155
 156 We recommend you do not mix the use of the two types of files. Further, it is
 157 better not to use the integrated :file:`frr.conf` file, as any syntax error in
 158 it can lead to /all/ of your daemons being unable to start up. Per daemon files
 159 are more robust as impact of errors in configuration are limited to the daemon
 160 in whose file the error is made.
 161
 162 .. clicmd:: service integrated-vtysh-config
 163
 164
 165    Control whether integrated :file:`frr.conf` file is written when
 166    'write file' is issued.
 167
 168    These commands need to be placed in :file:`vtysh.conf` to have any effect.
 169    Note that since :file:`vtysh.conf` is not written by FRR itself, they
 170    therefore need to be manually placed in that file.
 171
 172    This command has 3 states:
 173
 174
 175    service integrated-vtysh-config
 176       *vtysh* will always write :file:`frr.conf`.
 177
 178
 179    no service integrated-vtysh-config
 180       *vtysh* will never write :file:`frr.conf`; instead it will ask
 181       daemons to write their individual configuration files.
 182
 183    Neither option present (default)
 184       *vtysh* will check whether :file:`frr.conf` exists. If it does,
 185       configuration writes will update that file. Otherwise, writes are performed
 186       through the individual daemons.
 187
 188    This command is primarily intended for packaging/distribution purposes, to
 189    preset one of the two operating modes and ensure consistent operation across
 190    installations.
 191
 192 .. clicmd:: write integrated
 193
 194    Unconditionally (regardless of ``service integrated-vtysh-config`` setting)
 195    write out integrated :file:`frr.conf` file through *watchfrr*. If *watchfrr*
 196    is not running, this command is unavailable.
 197
 198 .. warning::
 199
 200    Configuration changes made while some daemon is not running will be
 201    invisible to that daemon. The daemon will start up with its saved
 202    configuration (either in its individual configuration file, or in
 203    :file:`frr.conf`).  This is particularly troublesome for route-maps and
 204    prefix lists, which would otherwise be synchronized between daemons.
 205