..
Copyright (c) 2021 Varnish Software AS
SPDX-License-Identifier: BSD-2-Clause
See LICENSE file for full text of license
.. role:: ref(emphasis)
.. _ref_cli_api:
===========================================
VCLI protocol - Scripting the CLI interface
===========================================
The Varnish CLI has a few bells&whistles when used as an API.
First: `vcli.h` contains magic numbers.
Second: If you use `varnishadm` to connect to `varnishd` for
API purposes, use the `-p` argument to get "pass" mode.
In "pass" mode, or with direct CLI connections (more below), the
first line of responses is always exactly 13 bytes long, including
the NL, and it contains two numbers: The status code and the count
of bytes in the "body" of the response::
200?19???????
PONG?1613397488?1.0
This makes parsing the response unambiguous, even in cases like this
where the response does not end with a NL.
The varnishapi library contains functions to implement the basics of
the CLI protocol, for more, see the `vcli.h` include file.
.. _ref_remote_cli:
Local and remote CLI connections
--------------------------------
The ``varnishd`` process receives the CLI commands via TCP connections
which require PSK authentication (see below), but which provide no secrecy.
"No secrecy" means that if you configure these TCP connections to run
across a network, anybody who can sniff packets can see your CLI
commands. If you need secrecy, use ``ssh`` to run ``varnishadm`` or
to tunnel the TCP connection.
By default `varnishd` binds to ``localhost`` and ask the kernel to
assign a random port number. The resulting listen address is
stored in the shared memory, where the ``varnishadm`` program finds it.
You can configure ``varnishd`` to listen to a specific address with
the ``-T`` argument, this will also be written to shared memory, so
``varnishadm`` keeps working::
# Bind to internal network
varnishd -T 192.168.10.21:3245
You can also configure ``varnishd`` to actively open a TCP connection
to another "controller" program, with the ``-M`` argument.
Finally, when run in "debug mode" with the ``-d`` argument, ``varnishd``
will stay in the foreground and turn stdin/stdout into a CLI connection.
.. _ref_psk_auth:
Authentication CLI connections
------------------------------
CLI connections to `varnishd` are authenticated with a "pre-shared-key"
authentication scheme, where the other end must prove they know
*the contents of* the secret file ``varnishd`` uses.
They do not have to read the precise same file on that specific
computer, they could read an entirely different file on a different
computer or fetch the secret from a server.
The name of the file can be configured with the ``-S`` option, and
``varnishd`` records the name in shared memory, so ``varnishadm``
can find it.
As a bare minimum ``varnishd`` needs to be able to read the file,
but other than that, it can be restricted any way you want.
Since it is not the file, but only the content of it that matter,
you can make the file unreadable by everybody, and instead place
a copy of the file in the home directories of the authorized users.
The file is read only at the moment when the `auth` CLI command is
issued and the contents is not cached in `varnishd`, so you can
change it as often as you want.
An authenticated session looks like this:
.. code-block:: text
critter phk> telnet localhost 1234
Trying ::1...
Trying 127.0.0.1...
Connected to localhost.
Escape character is '^]'.
107 59
ixslvvxrgkjptxmcgnnsdxsvdmvfympg
Authentication required.
auth 455ce847f0073c7ab3b1465f74507b75d3dc064c1e7de3b71e00de9092fdc89a
200 279
-----------------------------
Varnish Cache CLI 1.0
-----------------------------
FreeBSD,13.0-CURRENT,amd64,-jnone,-sdefault,-sdefault,-hcritbit
varnish-trunk revision 89a558e56390d425c52732a6c94087eec9083115
Type 'help' for command list.
Type 'quit' to close CLI session.
Type 'start' to launch worker process.
The CLI status of 107 indicates that authentication is necessary. The
first 32 characters of the response text is the challenge
"ixsl...mpg". The challenge is randomly generated for each CLI
connection, and changes each time a 107 is emitted.
The most recently emitted challenge must be used for calculating the
authenticator "455c¡c89a".
The authenticator is calculated by applying the SHA256 function to the
following byte sequence:
* Challenge string
* Newline (0x0a) character.
* Contents of the secret file
* Challenge string
* Newline (0x0a) character.
and dumping the resulting digest in lower-case hex.
In the above example, the secret file contains ``foo\n`` and thus:
.. code-block:: text
critter phk> hexdump secret
00000000 66 6f 6f 0a |foo.|
00000004
critter phk> cat > tmpfile
ixslvvxrgkjptxmcgnnsdxsvdmvfympg
foo
ixslvvxrgkjptxmcgnnsdxsvdmvfympg
^D
critter phk> hexdump -C tmpfile
00000000 69 78 73 6c 76 76 78 72 67 6b 6a 70 74 78 6d 63 |ixslvvxrgkjptxmc|
00000010 67 6e 6e 73 64 78 73 76 64 6d 76 66 79 6d 70 67 |gnnsdxsvdmvfympg|
00000020 0a 66 6f 6f 0a 69 78 73 6c 76 76 78 72 67 6b 6a |.foo.ixslvvxrgkj|
00000030 70 74 78 6d 63 67 6e 6e 73 64 78 73 76 64 6d 76 |ptxmcgnnsdxsvdmv|
00000040 66 79 6d 70 67 0a |fympg.|
00000046
critter phk> sha256 tmpfile
SHA256 (tmpfile) = 455ce847f0073c7ab3b1465f74507b75d3dc064c1e7de3b71e00de9092fdc89a
critter phk> openssl dgst -sha256 < tmpfile
455ce847f0073c7ab3b1465f74507b75d3dc064c1e7de3b71e00de9092fdc89a
The sourcefile `lib/libvarnish/cli_auth.c` contains a useful function
which calculates the response, given an open filedescriptor to the
secret file, and the challenge string.
See also:
---------
* :ref:`varnishadm(1)`
* :ref:`varnishd(1)`
* :ref:`vcl(7)`
Henceforth, whatever our philosopher says about Matter will apply to extension and to extension alone. It cannot be apprehended by sight, nor by hearing, nor by smell, nor by taste, for it is neither colour, nor sound, nor odour, nor juice. Neither can it be touched, for it is not a body, but it becomes corporeal on being blended with sensible qualities. And, in a later essay, he describes it as receiving all things and letting them depart again without retaining the slightest trace of their presence.483 Why then, it may be asked, if Plotinus meant extension, could he not say so at once, and save us all this trouble in hunting out his meaning? There were very good reasons why he should not. In the first place, he wished to express himself, so far as possible, in Aristotelian phraseology, and this was incompatible with the reduction of Matter to extension. In the next place, the idea of an infinite void had been already appropriated by the Epicureans, to whose system he was bitterly opposed. And, finally, the extension of ordinary327 experience had not the absolute generality which was needed in order to bring Matter into relation with that ultimate abstraction whence, like everything else, it has now to be derived. That the millionaire was genuine, ¡°in person and not a caricature,¡± as Dick put it, was evident. Both the nurse, his relative, and his wife, were chatting with him as Jeff delivered the heavy packed ball made up of the gum. 233 "I guess not," said Landor, tolerantly, as he turned[Pg 106] his horse over to his orderly; "but, anyway," he added to Ellton, "we had a picnic¡ªof a sort." Si, unable to think of anything better, went with him. The train had stopped on a switch, and seemed likely to rust fast to the rails, from the way other trains were going by in both directions. The bridge gang, under charge of a burly, red-faced young Englishman, was in the rear car, with their tools, equipments, bedding and cooking utensils. THE DEACON HAS SOME EXPERIENCES WITH THE QUADRUPED. "You are not within a mile of the truth. I know it. Look here: I believe that is Gen. Rosecrans's own cow. She's gone, and I got an order to look around for her. I've never seen her, but from the description given me I believe that's she. Who brought her here?" "Deacon, these brothers and sisters who have come here with me to-night are, like myself, deeply interested in the moral condition of the army, where we all have sons or kinsmen. Now, can't you sit right there and tell us of your observations and experiences, as a Christian man and father, from day to day, of every day that you were down there? Tell us everything, just as it happened each day, that we may be able to judge for ourselves." HAS AN ENCOUNTER WITH THE PROVOST-MARSHAL. "Wonder which one o' them is the 200th Injianny's?" said Si to Shorty. "And your mother, and Harry?" The daughter must be the girl who was talking to him now. She sat on a little stool by the fire, and had brought out some sewing. "Over at Grandturzel¡ªcan't see wot's burning from here. Git buckets and come!" These things, however, gave little concern to the worthy who commanded the Kentish division. Tyler, though an excellent blacksmith, possessed few of the qualities requisite for forming a good general. Provided there was no very sensible diminution in the number of his followers, he cared not a straw for the score or two who, after quarrelling, or perhaps fighting, withdrew in such disgust that they vowed rather to pay the full tax for ever than submit to the insolence of the rebels. One man could fight as well as another, reasoned he; and, provided he was obeyed, what mattered it by whom. Dick went and Tom came¡ªit was sure to be all one in the end. But this burst of indignation soon passed away, and upon the suggestion of the prudent Sir Robert Hailes, he sent an evasive answer, with a command that the Commons should attend him at Windsor on the Sunday following. That it was a stratagem to gain entrance to the Tower, was the opinion of several, but, after much discussion, it was decided that the man should be admitted, and that the monk should be exhibited merely to intimidate the rebels, until the result of this promised communication should be known. HoMEŮͬÐÔÁµcbcb
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