在踩了一天的坑之後，向迫不及待的寫下這篇博客，以防後面的不時之需。
首先，強調一下，本次主要講的是MQTT協議下mosquitto-server的TLS單向加密過程，也就是隻認證服務器不認證客戶端的過程。
在講之前，還有一點需要說清楚的是，作爲SSL加密傳輸方式，雙向加密的這個過程，苛刻一點的話，對於客戶端的加密是有一定的前提限制--------->客戶端數量非常的小（個位數計算）。詳細解釋請參考另一篇博客，這裏就不在贅述了，只是說清楚前提和內容。
那麼下面就TLS在mosquitto的單向加密詳細講解一下。
一、準備工作。
工慾善其事必先利其器，所以要先做好準備工作。這個是非常重要，本人就是因爲前期的準備工作不充分，造成自己走了一定的彎路。
首先，需要準備至少準備兩臺虛擬機。建議操作的方法是先安裝好一臺虛擬機，然後克隆一下就可以。
虛擬機首先要安裝openssl環境，輸入openssl version 查看你的版本，如果輸入之後無法使用該命令，或者輸出的不是如圖，那麼，你應當先安裝OpenSSL環境。使用sudo apt-get install openssl ，之後使用 sudo apt-get install libssl-dev 安裝開發環境。安裝好之後在用OpenSSL version 驗證你的版本。
安裝好OpenSSL 之後，就可以，下面就是安裝mosquitto了。這個已經介紹過了，博文https://blog.csdn.net/sullivan_jia/article/details/80089187
之後就是，將上面安裝好的虛擬機複製一臺）（原有的主機我們命名爲A 被複制的主機我們命名爲B）。使用 sudo vi /etc/hostname 修改主機名。使用ifconfig 查看兩個主機的ip是否相同。然後，在B中使用命令 ssh xxx.xxx.xxx.xxx（這裏替換成A的ip地址）。之後在A中用上述命令，ssh B，保證兩者可以正常連接。
上述過程完成後就可以，開始下一步了。
二、加密工作
學會了使用mosquitto的簡單使用後，下面開始正式的單向加密過程。
首先，大概講解一下流程。我們先使用B生成證書，傳到A當中，A用證書給B簽名，然後使用A的證書去驗證B，從而達到單項加密的過程。
1）在B中生成證書
首先，在B當中，生成一個CA證書，使用如下命令：
openssl req -new -x509 -days 36500 -extensions v3_ca -keyout ca.key -out ca.crt使用ls，會發現在當前目錄下，生成了兩個文件，一個是ca.key，另一個是ca.crt。
生成的時候其他的都好說，隨便寫，主要是Common Name ,這個就填寫B的ip地址。
之後，我們進入A虛擬機，將上述兩個文件拷貝到A當中。使用scp命令：
scp username@ipaddress:/patah ./這個命令是基本格式，解釋一下，username就是B的用戶名，在@後面加B的ip地址，如果你配置了hosts可以加B的主機名，冒號後面就是ca這個文件在B中地址，將這兩個文件拷貝到當前目錄。具體使用如下：
scp [email protected]:/home/jia/Desktop/ca/ca* ./ 這樣，就將這兩個文件複製過來了。
2）在A中爲Server端生成證書。
再將兩個文件拷貝過來之後，使用B的證書爲A簽發相應的證書。操作如下：
openssl genrsa -out server.key 2048之後，使用命令：
openssl req -out server.csr -key server.key -new 生成證書的簽發請求文件serverr.csr。這個同ca一樣，其他的都隨意填寫，主要是Common Name，這個填寫A的ip地址。
最後，使用命令：
openssl x509 -req -in server.csr -CA ca.crt -CAkey ca.key -CAcreateserial -out server.crt -days 36500輸入在填寫ca時填寫的密碼，完成對server端的簽發。
三、驗證
完成上述的操作，基本就搞定了，剩下的就是修改一下配置文件。在配置文件中添加相應的路徑，路徑我會在最後的附件部分給出。
驗證的過程也比較簡單，首先是啓動服務器--->訂閱消息--->發佈消息：
使用命令：
mosquitto_sub -t 'topic' -h 192.168.221.130 --tls-version tlsv1 --cafile /home/jia/Desktop/ca/ca.crt --insecure -p 8883訂閱一個名爲'topic'的主題，表明版本爲tlsv1 ，添加ca的驗證文件路徑。
之後，使用命令：
mosquitto_pub -t 'topic' -m 'when use ssl---->msg1' -h 192.168.221.130 --tls-version tlsv1 --cafile /home/jia/Desktop/ca/ca.crt -p 8883 -q2發佈質量等級爲QoS爲2的一條消息。
到此，基本就完成了單向加密的過程！
但是，有幾點要強調的是，必須使用--tls-version tlsv1來表明版本，默認爲1.2實際上是1.1，不表明的話，會提示版本錯誤；也要表明IP地址，默認是127.0.0.1不標明的戶也會報錯，最後就是切記標註8883端口。
四、附錄
下面是配置文件附錄，供大家參考。
# Config file for mosquitto
#
# See mosquitto.conf(5) for more information.
#
# Default values are shown, uncomment to change.
#
# Use the # character to indicate a comment, but only if it is the
# very first character on the line.
# =================================================================
# General configuration
# =================================================================
# Time in seconds to wait before resending an outgoing QoS=1 or
# QoS=2 message.
#retry_interval 20
# Time in seconds between updates of the $SYS tree.
# Set to 0 to disable the publishing of the $SYS tree.
#sys_interval 10
# Time in seconds between cleaning the internal message store of
# unreferenced messages. Lower values will result in lower memory
# usage but more processor time, higher values will have the
# opposite effect.
# Setting a value of 0 means the unreferenced messages will be
# disposed of as quickly as possible.
#store_clean_interval 10
# Write process id to a file. Default is a blank string which means
# a pid file shouldn't be written.
# This should be set to /var/run/mosquitto.pid if mosquitto is
# being run automatically on boot with an init script and
# start-stop-daemon or similar.
#pid_file
# When run as root, drop privileges to this user and its primary
# group.
# Leave blank to stay as root, but this is not recommended.
# If run as a non-root user, this setting has no effect.
# Note that on Windows this has no effect and so mosquitto should
# be started by the user you wish it to run as.
user jia
# The maximum number of QoS 1 and 2 messages currently inflight per
# client.
# This includes messages that are partway through handshakes and
# those that are being retried. Defaults to 20. Set to 0 for no
# maximum. Setting to 1 will guarantee in-order delivery of QoS 1
# and 2 messages.
#max_inflight_messages 20
# The maximum number of QoS 1 and 2 messages to hold in a queue
# above those that are currently in-flight. Defaults to 100. Set
# to 0 for no maximum (not recommended).
# See also queue_qos0_messages.
#max_queued_messages 100
# Set to true to queue messages with QoS 0 when a persistent client is
# disconnected. These messages are included in the limit imposed by
# max_queued_messages.
# Defaults to false.
# This is a non-standard option for the MQTT v3.1 spec but is allowed in
# v3.1.1.
#queue_qos0_messages false
# This option sets the maximum publish payload size that the broker will allow.
# Received messages that exceed this size will not be accepted by the broker.
# The default value is 0, which means that all valid MQTT messages are
# accepted. MQTT imposes a maximum payload size of 268435455 bytes.
#message_size_limit 0
# This option controls whether a client is allowed to connect with a zero
# length client id or not. This option only affects clients using MQTT v3.1.1
# and later. If set to false, clients connecting with a zero length client id
# are disconnected. If set to true, clients will be allocated a client id by
# the broker. This means it is only useful for clients with clean session set
# to true.
#allow_zero_length_clientid true
# If allow_zero_length_clientid is true, this option allows you to set a prefix
# to automatically generated client ids to aid visibility in logs.
#auto_id_prefix
# This option allows persistent clients (those with clean session set to false)
# to be removed if they do not reconnect within a certain time frame.
#
# This is a non-standard option in MQTT V3.1 but allowed in MQTT v3.1.1.
#
# Badly designed clients may set clean session to false whilst using a randomly
# generated client id. This leads to persistent clients that will never
# reconnect. This option allows these clients to be removed.
#
# The expiration period should be an integer followed by one of h d w m y for
# hour, day, week, month and year respectively. For example
#
# persistent_client_expiration 2m
# persistent_client_expiration 14d
# persistent_client_expiration 1y
#
# The default if not set is to never expire persistent clients.
#persistent_client_expiration
# If a client is subscribed to multiple subscriptions that overlap, e.g. foo/#
# and foo/+/baz , then MQTT expects that when the broker receives a message on
# a topic that matches both subscriptions, such as foo/bar/baz, then the client
# should only receive the message once.
# Mosquitto keeps track of which clients a message has been sent to in order to
# meet this requirement. The allow_duplicate_messages option allows this
# behaviour to be disabled, which may be useful if you have a large number of
# clients subscribed to the same set of topics and are very concerned about
# minimising memory usage.
# It can be safely set to true if you know in advance that your clients will
# never have overlapping subscriptions, otherwise your clients must be able to
# correctly deal with duplicate messages even when then have QoS=2.
#allow_duplicate_messages false
# The MQTT specification requires that the QoS of a message delivered to a
# subscriber is never upgraded to match the QoS of the subscription. Enabling
# this option changes this behaviour. If upgrade_outgoing_qos is set true,
# messages sent to a subscriber will always match the QoS of its subscription.
# This is a non-standard option explicitly disallowed by the spec.
#upgrade_outgoing_qos false
# =================================================================
# Default listener
# =================================================================
# IP address/hostname to bind the default listener to. If not
# given, the default listener will not be bound to a specific
# address and so will be accessible to all network interfaces.
# bind_address ip-address/host name
#bind_address 0.0.0.0
# Port to use for the default listener.
listener 8883
# The maximum number of client connections to allow. This is
# a per listener setting.
# Default is -1, which means unlimited connections.
# Note that other process limits mean that unlimited connections
# are not really possible. Typically the default maximum number of
# connections possible is around 1024.
#max_connections -1
# Choose the protocol to use when listening.
# This can be either mqtt or websockets.
# Websockets support is currently disabled by default at compile time.
# Certificate based TLS may be used with websockets, except that
# only the cafile, certfile, keyfile and ciphers options are supported.
#protocol websockets
# When a listener is using the websockets protocol, it is possible to serve
# http data as well. Set http_dir to a directory which contains the files you
# wish to serve. If this option is not specified, then no normal http
# connections will be possible.
#http_dir
# Set use_username_as_clientid to true to replace the clientid that a client
# connected with with its username. This allows authentication to be tied to
# the clientid, which means that it is possible to prevent one client
# disconnecting another by using the same clientid.
# If a client connects with no username it will be disconnected as not
# authorised when this option is set to true.
# Do not use in conjunction with clientid_prefixes.
# See also use_identity_as_username.
#use_username_as_clientid
# -----------------------------------------------------------------
# Certificate based SSL/TLS support
# -----------------------------------------------------------------
# The following options can be used to enable SSL/TLS support for
# this listener. Note that the recommended port for MQTT over TLS
# is 8883, but this must be set manually.
#
# See also the mosquitto-tls man page.
# At least one of cafile or capath must be defined. They both
# define methods of accessing the PEM encoded Certificate
# Authority certificates that have signed your server certificate
# and that you wish to trust.
# cafile defines the path to a file containing the CA certificates.
# capath defines a directory that will be searched for files
# containing the CA certificates. For capath to work correctly, the
# certificate files must have ".crt" as the file ending and you must run
# "c_rehash <path to capath>" each time you add/remove a certificate.
#cafile
#capath
# Path to the PEM encoded server certificate.
#certfile
# Path to the PEM encoded keyfile.
#keyfile
cafile /home/jia/Desktop/ca/ca.crt
certfile /home/jia/Desktop/ca/server.crt
keyfile /home/jia/Desktop/ca/server.key
tls_version tlsv1
# This option defines the version of the TLS protocol to use for this listener.
# The default value allows v1.2, v1.1 and v1.0, if they are all supported by
# the version of openssl that the broker was compiled against. For openssl >=
# 1.0.1 the valid values are tlsv1.2 tlsv1.1 and tlsv1. For openssl < 1.0.1 the
# valid values are tlsv1.
#tls_version
# By default a TLS enabled listener will operate in a similar fashion to a
# https enabled web server, in that the server has a certificate signed by a CA
# and the client will verify that it is a trusted certificate. The overall aim
# is encryption of the network traffic. By setting require_certificate to true,
# the client must provide a valid certificate in order for the network
# connection to proceed. This allows access to the broker to be controlled
# outside of the mechanisms provided by MQTT.
require_certificate false
# If require_certificate is true, you may set use_identity_as_username to true
# to use the CN value from the client certificate as a username. If this is
# true, the password_file option will not be used for this listener.
#use_identity_as_username false
# If you have require_certificate set to true, you can create a certificate
# revocation list file to revoke access to particular client certificates. If
# you have done this, use crlfile to point to the PEM encoded revocation file.
#crlfile
# If you wish to control which encryption ciphers are used, use the ciphers
# option. The list of available ciphers can be obtained using the "openssl
# ciphers" command and should be provided in the same format as the output of
# that command.
# If unset defaults to DEFAULT:!aNULL:!eNULL:!LOW:!EXPORT:!SSLv2:@STRENGTH
#ciphers DEFAULT:!aNULL:!eNULL:!LOW:!EXPORT:!SSLv2:@STRENGTH
# -----------------------------------------------------------------
# Pre-shared-key based SSL/TLS support
# -----------------------------------------------------------------
# The following options can be used to enable PSK based SSL/TLS support for
# this listener. Note that the recommended port for MQTT over TLS is 8883, but
# this must be set manually.
#
# See also the mosquitto-tls man page and the "Certificate based SSL/TLS
# support" section. Only one of certificate or PSK encryption support can be
# enabled for any listener.
# The psk_hint option enables pre-shared-key support for this listener and also
# acts as an identifier for this listener. The hint is sent to clients and may
# be used locally to aid authentication. The hint is a free form string that
# doesn't have much meaning in itself, so feel free to be creative.
# If this option is provided, see psk_file to define the pre-shared keys to be
# used or create a security plugin to handle them.
#psk_hint
# Set use_identity_as_username to have the psk identity sent by the client used
# as its username. Authentication will be carried out using the PSK rather than
# the MQTT username/password and so password_file will not be used for this
# listener.
#use_identity_as_username false
# When using PSK, the encryption ciphers used will be chosen from the list of
# available PSK ciphers. If you want to control which ciphers are available,
# use the "ciphers" option. The list of available ciphers can be obtained
# using the "openssl ciphers" command and should be provided in the same format
# as the output of that command.
#ciphers
# =================================================================
# Extra listeners
# =================================================================
# Listen on a port/ip address combination. By using this variable
# multiple times, mosquitto can listen on more than one port. If
# this variable is used and neither bind_address nor port given,
# then the default listener will not be started.
# The port number to listen on must be given. Optionally, an ip
# address or host name may be supplied as a second argument. In
# this case, mosquitto will attempt to bind the listener to that
# address and so restrict access to the associated network and
# interface. By default, mosquitto will listen on all interfaces.
# Note that for a websockets listener it is not possible to bind to a host
# name.
# listener port-number [ip address/host name]
#listener
# The maximum number of client connections to allow. This is
# a per listener setting.
# Default is -1, which means unlimited connections.
# Note that other process limits mean that unlimited connections
# are not really possible. Typically the default maximum number of
# connections possible is around 1024.
#max_connections -1
# The listener can be restricted to operating within a topic hierarchy using
# the mount_point option. This is achieved be prefixing the mount_point string
# to all topics for any clients connected to this listener. This prefixing only
# happens internally to the broker; the client will not see the prefix.
#mount_point
# Choose the protocol to use when listening.
# This can be either mqtt or websockets.
# Certificate based TLS may be used with websockets, except that only the
# cafile, certfile, keyfile and ciphers options are supported.
#protocol mqtt
# When a listener is using the websockets protocol, it is possible to serve
# http data as well. Set http_dir to a directory which contains the files you
# wish to serve. If this option is not specified, then no normal http
# connections will be possible.
#http_dir
# Set use_username_as_clientid to true to replace the clientid that a client
# connected with with its username. This allows authentication to be tied to
# the clientid, which means that it is possible to prevent one client
# disconnecting another by using the same clientid.
# If a client connects with no username it will be disconnected as not
# authorised when this option is set to true.
# Do not use in conjunction with clientid_prefixes.
# See also use_identity_as_username.
#use_username_as_clientid
# -----------------------------------------------------------------
# Certificate based SSL/TLS support
# -----------------------------------------------------------------
# The following options can be used to enable certificate based SSL/TLS support
# for this listener. Note that the recommended port for MQTT over TLS is 8883,
# but this must be set manually.
#
# See also the mosquitto-tls man page and the "Pre-shared-key based SSL/TLS
# support" section. Only one of certificate or PSK encryption support can be
# enabled for any listener.
# At least one of cafile or capath must be defined to enable certificate based
# TLS encryption. They both define methods of accessing the PEM encoded
# Certificate Authority certificates that have signed your server certificate
# and that you wish to trust.
# cafile defines the path to a file containing the CA certificates.
# capath defines a directory that will be searched for files
# containing the CA certificates. For capath to work correctly, the
# certificate files must have ".crt" as the file ending and you must run
# "c_rehash <path to capath>" each time you add/remove a certificate.
#cafile
#capath
# Path to the PEM encoded server certificate.
#certfile
# Path to the PEM encoded keyfile.
#keyfile
# By default an TLS enabled listener will operate in a similar fashion to a
# https enabled web server, in that the server has a certificate signed by a CA
# and the client will verify that it is a trusted certificate. The overall aim
# is encryption of the network traffic. By setting require_certificate to true,
# the client must provide a valid certificate in order for the network
# connection to proceed. This allows access to the broker to be controlled
# outside of the mechanisms provided by MQTT.
#require_certificate false
# If require_certificate is true, you may set use_identity_as_username to true
# to use the CN value from the client certificate as a username. If this is
# true, the password_file option will not be used for this listener.
#use_identity_as_username false
# If you have require_certificate set to true, you can create a certificate
# revocation list file to revoke access to particular client certificates. If
# you have done this, use crlfile to point to the PEM encoded revocation file.
#crlfile
# If you wish to control which encryption ciphers are used, use the ciphers
# option. The list of available ciphers can be optained using the "openssl
# ciphers" command and should be provided in the same format as the output of
# that command.
#ciphers
# -----------------------------------------------------------------
# Pre-shared-key based SSL/TLS support
# -----------------------------------------------------------------
# The following options can be used to enable PSK based SSL/TLS support for
# this listener. Note that the recommended port for MQTT over TLS is 8883, but
# this must be set manually.
#
# See also the mosquitto-tls man page and the "Certificate based SSL/TLS
# support" section. Only one of certificate or PSK encryption support can be
# enabled for any listener.
# The psk_hint option enables pre-shared-key support for this listener and also
# acts as an identifier for this listener. The hint is sent to clients and may
# be used locally to aid authentication. The hint is a free form string that
# doesn't have much meaning in itself, so feel free to be creative.
# If this option is provided, see psk_file to define the pre-shared keys to be
# used or create a security plugin to handle them.
#psk_hint
# Set use_identity_as_username to have the psk identity sent by the client used
# as its username. Authentication will be carried out using the PSK rather than
# the MQTT username/password and so password_file will not be used for this
# listener.
#use_identity_as_username false
# When using PSK, the encryption ciphers used will be chosen from the list of
# available PSK ciphers. If you want to control which ciphers are available,
# use the "ciphers" option. The list of available ciphers can be optained
# using the "openssl ciphers" command and should be provided in the same format
# as the output of that command.
#ciphers
# =================================================================
# Persistence
# =================================================================
# If persistence is enabled, save the in-memory database to disk
# every autosave_interval seconds. If set to 0, the persistence
# database will only be written when mosquitto exits. See also
# autosave_on_changes.
# Note that writing of the persistence database can be forced by
# sending mosquitto a SIGUSR1 signal.
#autosave_interval 1800
# If true, mosquitto will count the number of subscription changes, retained
# messages received and queued messages and if the total exceeds
# autosave_interval then the in-memory database will be saved to disk.
# If false, mosquitto will save the in-memory database to disk by treating
# autosave_interval as a time in seconds.
#autosave_on_changes false
# Save persistent message data to disk (true/false).
# This saves information about all messages, including
# subscriptions, currently in-flight messages and retained
# messages.
# retained_persistence is a synonym for this option.
#persistence false
# The filename to use for the persistent database, not including
# the path.
#persistence_file mosquitto.db
# Location for persistent database. Must include trailing /
# Default is an empty string (current directory).
# Set to e.g. /var/lib/mosquitto/ if running as a proper service on Linux or
# similar.
#persistence_location
# =================================================================
# Logging
# =================================================================
# Places to log to. Use multiple log_dest lines for multiple
# logging destinations.
# Possible destinations are: stdout stderr syslog topic file
#
# stdout and stderr log to the console on the named output.
#
# syslog uses the userspace syslog facility which usually ends up
# in /var/log/messages or similar.
#
# topic logs to the broker topic '$SYS/broker/log/<severity>',
# where severity is one of D, E, W, N, I, M which are debug, error,
# warning, notice, information and message. Message type severity is used by
# the subscribe/unsubscribe log_types and publishes log messages to
# $SYS/broker/log/M/susbcribe or $SYS/broker/log/M/unsubscribe.
#
# The file destination requires an additional parameter which is the file to be
# logged to, e.g. "log_dest file /var/log/mosquitto.log". The file will be
# closed and reopened when the broker receives a HUP signal. Only a single file
# destination may be configured.
#
# Note that if the broker is running as a Windows service it will default to
# "log_dest none" and neither stdout nor stderr logging is available.
# Use "log_dest none" if you wish to disable logging.
#log_dest stderr
# If using syslog logging (not on Windows), messages will be logged to the
# "daemon" facility by default. Use the log_facility option to choose which of
# local0 to local7 to log to instead. The option value should be an integer
# value, e.g. "log_facility 5" to use local5.
#log_facility
# Types of messages to log. Use multiple log_type lines for logging
# multiple types of messages.
# Possible types are: debug, error, warning, notice, information,
# none, subscribe, unsubscribe, websockets, all.
# Note that debug type messages are for decoding the incoming/outgoing
# network packets. They are not logged in "topics".
#log_type error
#log_type warning
#log_type notice
#log_type information
# Change the websockets logging level. This is a global option, it is not
# possible to set per listener. This is an integer that is interpreted by
# libwebsockets as a bit mask for its lws_log_levels enum. See the
# libwebsockets documentation for more details. "log_type websockets" must also
# be enabled.
#websockets_log_level 0
# If set to true, client connection and disconnection messages will be included
# in the log.
#connection_messages true
# If set to true, add a timestamp value to each log message.
#log_timestamp true
# =================================================================
# Security
# =================================================================
# If set, only clients that have a matching prefix on their
# clientid will be allowed to connect to the broker. By default,
# all clients may connect.
# For example, setting "secure-" here would mean a client "secure-
# client" could connect but another with clientid "mqtt" couldn't.
#clientid_prefixes
# Boolean value that determines whether clients that connect
# without providing a username are allowed to connect. If set to
# false then a password file should be created (see the
# password_file option) to control authenticated client access.
# Defaults to true.
allow_anonymous true
# In addition to the clientid_prefixes, allow_anonymous and TLS
# authentication options, username based authentication is also
# possible. The default support is described in "Default
# authentication and topic access control" below. The auth_plugin
# allows another authentication method to be used.
# Specify the path to the loadable plugin and see the
# "Authentication and topic access plugin options" section below.
#auth_plugin
# If auth_plugin_deny_special_chars is true, the default, then before an ACL
# check is made, the username/client id of the client needing the check is
# searched for the presence of either a '+' or '#' character. If either of
# these characters is found in either the username or client id, then the ACL
# check is denied before it is sent to the plugin.o
#
# This check prevents the case where a malicious user could circumvent an ACL
# check by using one of these characters as their username or client id. This
# is the same issue as was reported with mosquitto itself as CVE-2017-7650.
#
# If you are entirely sure that the plugin you are using is not vulnerable to
# this attack (i.e. if you never use usernames or client ids in topics) then
# you can disable this extra check and have all ACL checks delivered to your
# plugin by setting auth_plugin_deny_special_chars to false.
#auth_plugin_deny_special_chars true
# -----------------------------------------------------------------
# Default authentication and topic access control
# -----------------------------------------------------------------
# Control access to the broker using a password file. This file can be
# generated using the mosquitto_passwd utility. If TLS support is not compiled
# into mosquitto (it is recommended that TLS support should be included) then
# plain text passwords are used, in which case the file should be a text file
# with lines in the format:
# username:password
# The password (and colon) may be omitted if desired, although this
# offers very little in the way of security.
#
# See the TLS client require_certificate and use_identity_as_username options
# for alternative authentication options.
#password_file
# Access may also be controlled using a pre-shared-key file. This requires
# TLS-PSK support and a listener configured to use it. The file should be text
# lines in the format:
# identity:key
# The key should be in hexadecimal format without a leading "0x".
#psk_file
# Control access to topics on the broker using an access control list
# file. If this parameter is defined then only the topics listed will
# have access.
# If the first character of a line of the ACL file is a # it is treated as a
# comment.
# Topic access is added with lines of the format:
#
# topic [read|write|readwrite] <topic>
#
# The access type is controlled using "read", "write" or "readwrite". This
# parameter is optional (unless <topic> contains a space character) - if not
# given then the access is read/write. <topic> can contain the + or #
# wildcards as in subscriptions.
#
# The first set of topics are applied to anonymous clients, assuming
# allow_anonymous is true. User specific topic ACLs are added after a
# user line as follows:
#
# user <username>
#
# The username referred to here is the same as in password_file. It is
# not the clientid.
#
#
# If is also possible to define ACLs based on pattern substitution within the
# topic. The patterns available for substition are:
#
# %c to match the client id of the client
# %u to match the username of the client
#
# The substitution pattern must be the only text for that level of hierarchy.
#
# The form is the same as for the topic keyword, but using pattern as the
# keyword.
# Pattern ACLs apply to all users even if the "user" keyword has previously
# been given.
#
# If using bridges with usernames and ACLs, connection messages can be allowed
# with the following pattern:
# pattern write $SYS/broker/connection/%c/state
#
# pattern [read|write|readwrite] <topic>
#
# Example:
#
# pattern write sensor/%u/data
#
#acl_file
# -----------------------------------------------------------------
# Authentication and topic access plugin options
# -----------------------------------------------------------------
# If the auth_plugin option above is used, define options to pass to the
# plugin here as described by the plugin instructions. All options named
# using the format auth_opt_* will be passed to the plugin, for example:
#
# auth_opt_db_host
# auth_opt_db_port
# auth_opt_db_username
# auth_opt_db_password
# =================================================================
# Bridges
# =================================================================
# A bridge is a way of connecting multiple MQTT brokers together.
# Create a new bridge using the "connection" option as described below. Set
# options for the bridges using the remaining parameters. You must specify the
# address and at least one topic to subscribe to.
# Each connection must have a unique name.
# The address line may have multiple host address and ports specified. See
# below in the round_robin description for more details on bridge behaviour if
# multiple addresses are used.
# The direction that the topic will be shared can be chosen by
# specifying out, in or both, where the default value is out.
# The QoS level of the bridged communication can be specified with the next
# topic option. The default QoS level is 0, to change the QoS the topic
# direction must also be given.
# The local and remote prefix options allow a topic to be remapped when it is
# bridged to/from the remote broker. This provides the ability to place a topic
# tree in an appropriate location.
# For more details see the mosquitto.conf man page.
# Multiple topics can be specified per connection, but be careful
# not to create any loops.
# If you are using bridges with cleansession set to false (the default), then
# you may get unexpected behaviour from incoming topics if you change what
# topics you are subscribing to. This is because the remote broker keeps the
# subscription for the old topic. If you have this problem, connect your bridge
# with cleansession set to true, then reconnect with cleansession set to false
# as normal.
#connection <name>
#address <host>[:<port>] [<host>[:<port>]]
#topic <topic> [[[out | in | both] qos-level] local-prefix remote-prefix]
# Set the version of the MQTT protocol to use with for this bridge. Can be one
# of mqttv31 or mqttv311. Defaults to mqttv31.
#bridge_protocol_version mqttv31
# If a bridge has topics that have "out" direction, the default behaviour is to
# send an unsubscribe request to the remote broker on that topic. This means
# that changing a topic direction from "in" to "out" will not keep receiving
# incoming messages. Sending these unsubscribe requests is not always
# desirable, setting bridge_attempt_unsubscribe to false will disable sending
# the unsubscribe request.
#bridge_attempt_unsubscribe true
# If the bridge has more than one address given in the address/addresses
# configuration, the round_robin option defines the behaviour of the bridge on
# a failure of the bridge connection. If round_robin is false, the default
# value, then the first address is treated as the main bridge connection. If
# the connection fails, the other secondary addresses will be attempted in
# turn. Whilst connected to a secondary bridge, the bridge will periodically
# attempt to reconnect to the main bridge until successful.
# If round_robin is true, then all addresses are treated as equals. If a
# connection fails, the next address will be tried and if successful will
# remain connected until it fails
#round_robin false
# Set the client id to use on the remote end of this bridge connection. If not
# defined, this defaults to 'name.hostname' where name is the connection name
# and hostname is the hostname of this computer.
# This replaces the old "clientid" option to avoid confusion. "clientid"
# remains valid for the time being.
#remote_clientid
# Set the clientid to use on the local broker. If not defined, this defaults to
# 'local.<clientid>'. If you are bridging a broker to itself, it is important
# that local_clientid and clientid do not match.
#local_clientid
# Set the clean session variable for this bridge.
# When set to true, when the bridge disconnects for any reason, all
# messages and subscriptions will be cleaned up on the remote
# broker. Note that with cleansession set to true, there may be a
# significant amount of retained messages sent when the bridge
# reconnects after losing its connection.
# When set to false, the subscriptions and messages are kept on the
# remote broker, and delivered when the bridge reconnects.
#cleansession false
# If set to true, publish notification messages to the local and remote brokers
# giving information about the state of the bridge connection. Retained
# messages are published to the topic $SYS/broker/connection/<clientid>/state
# unless the notification_topic option is used.
# If the message is 1 then the connection is active, or 0 if the connection has
# failed.
#notifications true
# Choose the topic on which notification messages for this bridge are
# published. If not set, messages are published on the topic
# $SYS/broker/connection/<clientid>/state
#notification_topic
# Set the keepalive interval for this bridge connection, in
# seconds.
#keepalive_interval 60
# Set the start type of the bridge. This controls how the bridge starts and
# can be one of three types: automatic, lazy and once. Note that RSMB provides
# a fourth start type "manual" which isn't currently supported by mosquitto.
#
# "automatic" is the default start type and means that the bridge connection
# will be started automatically when the broker starts and also restarted
# after a short delay (30 seconds) if the connection fails.
#
# Bridges using the "lazy" start type will be started automatically when the
# number of queued messages exceeds the number set with the "threshold"
# parameter. It will be stopped automatically after the time set by the
# "idle_timeout" parameter. Use this start type if you wish the connection to
# only be active when it is needed.
#
# A bridge using the "once" start type will be started automatically when the
# broker starts but will not be restarted if the connection fails.
#start_type automatic
# Set the amount of time a bridge using the automatic start type will wait
# until attempting to reconnect. Defaults to 30 seconds.
#restart_timeout 30
# Set the amount of time a bridge using the lazy start type must be idle before
# it will be stopped. Defaults to 60 seconds.
#idle_timeout 60
# Set the number of messages that need to be queued for a bridge with lazy
# start type to be restarted. Defaults to 10 messages.
# Must be less than max_queued_messages.
#threshold 10
# If try_private is set to true, the bridge will attempt to indicate to the
# remote broker that it is a bridge not an ordinary client. If successful, this
# means that loop detection will be more effective and that retained messages
# will be propagated correctly. Not all brokers support this feature so it may
# be necessary to set try_private to false if your bridge does not connect
# properly.
#try_private true
# Set the username to use when connecting to a broker that requires
# authentication.
# This replaces the old "username" option to avoid confusion. "username"
# remains valid for the time being.
#remote_username
# Set the password to use when connecting to a broker that requires
# authentication. This option is only used if remote_username is also set.
# This replaces the old "password" option to avoid confusion. "password"
# remains valid for the time being.
#remote_password
# -----------------------------------------------------------------
# Certificate based SSL/TLS support
# -----------------------------------------------------------------
# Either bridge_cafile or bridge_capath must be defined to enable TLS support
# for this bridge.
# bridge_cafile defines the path to a file containing the
# Certificate Authority certificates that have signed the remote broker
# certificate.
# bridge_capath defines a directory that will be searched for files containing
# the CA certificates. For bridge_capath to work correctly, the certificate
# files must have ".crt" as the file ending and you must run "c_rehash <path to
# capath>" each time you add/remove a certificate.
#bridge_cafile
#bridge_capath
# Path to the PEM encoded client certificate, if required by the remote broker.
#bridge_certfile
# Path to the PEM encoded client private key, if required by the remote broker.
#bridge_keyfile
# When using certificate based encryption, bridge_insecure disables
# verification of the server hostname in the server certificate. This can be
# useful when testing initial server configurations, but makes it possible for
# a malicious third party to impersonate your server through DNS spoofing, for
# example. Use this option in testing only. If you need to resort to using this
# option in a production environment, your setup is at fault and there is no
# point using encryption.
#bridge_insecure false
# -----------------------------------------------------------------
# PSK based SSL/TLS support
# -----------------------------------------------------------------
# Pre-shared-key encryption provides an alternative to certificate based
# encryption. A bridge can be configured to use PSK with the bridge_identity
# and bridge_psk options. These are the client PSK identity, and pre-shared-key
# in hexadecimal format with no "0x". Only one of certificate and PSK based
# encryption can be used on one
# bridge at once.
#bridge_identity
#bridge_psk
# =================================================================
# External config files
# =================================================================
# External configuration files may be included by using the
# include_dir option. This defines a directory that will be searched
# for config files. All files that end in '.conf' will be loaded as
# a configuration file. It is best to have this as the last option
# in the main file. This option will only be processed from the main
# configuration file. The directory specified must not contain the
# main configuration file.
#include_dir
# =================================================================
# rsmb options - unlikely to ever be supported
# =================================================================
#ffdc_output
#max_log_entries
#trace_level
#trace_output
