rpm -Uvh https://repo.zabbix.com/zabbix/5.0/rhel/8/x86_64/zabbix-release-5.0-1.el8.noarch.rpm
dnf clean all

dnf install -y zabbix-agent

systemctl restart zabbix-agent
systemctl enable zabbix-agent

zabbix-agent設定ファイルの主な変更項目について記載する。
各設定値の詳細説明は下記URLを参照すること。
日本語訳はバージョンが古いので、不足している項目は英語版で確認すること。
https://www.zabbix.com/documentation/2.2/jp/manual/appendix/config/zabbix_agentd

#変更
vi /etc/zabbix/zabbix_agentd.conf

#適用
systemctl restart zabbix-agent

#ログ確認
cat /var/log/zabbix/zabbix_agentd.log

Server=[zabbixサーバーのIPかホスト名]
通信の方向: zabbixserver → zabbixagent
ポート:10050/TCP(Agent側)
※ポートが開いていないとAgent起動に失敗する。

#変更不要
Server=127.0.0.1

通信の方向: zabbixagent → zabbixserver
ポート:10051/TCP(Server側)
※ポートが開いていないとログ監視ができない

#変更前
ServerActive=127.0.0.1

#変更後(ポート番号未記載の場合はデフォルトポート10051となる)
ServerActive=[zabbixサーバーのIPかホスト名]:[サーバのポート番号]

ホスト名の設定は、HostnameとHostnameItemの何れかで指定できる。
Agent側で指定するホスト名とZabbixのホスト登録で指定するホスト名を一致させる必要あり。
設定の優先度：Hostname＞HostnameItem

#変更例１(指定したホスト名が設定できる)
Hostname=[ホスト名]
# HostnameItem=system.hostname

#変更例２(自身のhostnameの値が設定される)
# Hostname=
HostnameItem=system.hostname

# This is a configuration file for Zabbix agent daemon (Unix)
# To get more information about Zabbix, visit http://www.zabbix.com

############ GENERAL PARAMETERS #################

### Option: PidFile
#       Name of PID file.
#
# Mandatory: no
# Default:
# PidFile=/tmp/zabbix_agentd.pid

PidFile=/var/run/zabbix/zabbix_agentd.pid

### Option: LogType
#       Specifies where log messages are written to:
#               system  - syslog
#               file    - file specified with LogFile parameter
#               console - standard output
#
# Mandatory: no
# Default:
# LogType=file

### Option: LogFile
#       Log file name for LogType 'file' parameter.
#
# Mandatory: yes, if LogType is set to file, otherwise no
# Default:
# LogFile=

LogFile=/var/log/zabbix/zabbix_agentd.log

### Option: LogFileSize
#       Maximum size of log file in MB.
#       0 - disable automatic log rotation.
#
# Mandatory: no
# Range: 0-1024
# Default:
# LogFileSize=1

LogFileSize=0

### Option: DebugLevel
#       Specifies debug level:
#       0 - basic information about starting and stopping of Zabbix processes
#       1 - critical information
#       2 - error information
#       3 - warnings
#       4 - for debugging (produces lots of information)
#       5 - extended debugging (produces even more information)
#
# Mandatory: no
# Range: 0-5
# Default:
# DebugLevel=3

### Option: SourceIP
#       Source IP address for outgoing connections.
#
# Mandatory: no
# Default:
# SourceIP=

### Option: AllowKey
#       Allow execution of item keys matching pattern.
#       Multiple keys matching rules may be defined in combination with DenyKey.
#       Key pattern is wildcard expression, which support "*" character to match any number of any characters in certain position. It might be used in both key name and key arguments.
#       Parameters are processed one by one according their appearance order.
#       If no AllowKey or DenyKey rules defined, all keys are allowed.
#
# Mandatory: no

### Option: DenyKey
#       Deny execution of items keys matching pattern.
#       Multiple keys matching rules may be defined in combination with AllowKey.
#       Key pattern is wildcard expression, which support "*" character to match any number of any characters in certain position. It might be used in both key name and key arguments.
#       Parameters are processed one by one according their appearance order.
#       If no AllowKey or DenyKey rules defined, all keys are allowed.
#       Unless another system.run[*] rule is specified DenyKey=system.run[*] is added by default.
#
# Mandatory: no
# Default:
# DenyKey=system.run[*]

### Option: EnableRemoteCommands - Deprecated, use AllowKey=system.run[*] or DenyKey=system.run[*] instead
#       Internal alias for AllowKey/DenyKey parameters depending on value:
#       0 - DenyKey=system.run[*]
#       1 - AllowKey=system.run[*]
#
# Mandatory: no

### Option: LogRemoteCommands
#       Enable logging of executed shell commands as warnings.
#       0 - disabled
#       1 - enabled
#
# Mandatory: no
# Default:
# LogRemoteCommands=0

##### Passive checks related

### Option: Server
#       List of comma delimited IP addresses, optionally in CIDR notation, or DNS names of Zabbix servers and Zabbix proxies.
#       Incoming connections will be accepted only from the hosts listed here.
#       If IPv6 support is enabled then '127.0.0.1', '::127.0.0.1', '::ffff:127.0.0.1' are treated equally
#       and '::/0' will allow any IPv4 or IPv6 address.
#       '0.0.0.0/0' can be used to allow any IPv4 address.
#       Example: Server=127.0.0.1,192.168.1.0/24,::1,2001:db8::/32,zabbix.example.com
#
# Mandatory: yes, if StartAgents is not explicitly set to 0
# Default:
# Server=

Server=127.0.0.1

### Option: ListenPort
#       Agent will listen on this port for connections from the server.
#
# Mandatory: no
# Range: 1024-32767
# Default:
# ListenPort=10050

### Option: ListenIP
#       List of comma delimited IP addresses that the agent should listen on.
#       First IP address is sent to Zabbix server if connecting to it to retrieve list of active checks.
#
# Mandatory: no
# Default:
# ListenIP=0.0.0.0

### Option: StartAgents
#       Number of pre-forked instances of zabbix_agentd that process passive checks.
#       If set to 0, disables passive checks and the agent will not listen on any TCP port.
#
# Mandatory: no
# Range: 0-100
# Default:
# StartAgents=3

##### Active checks related

### Option: ServerActive
#       List of comma delimited IP:port (or DNS name:port) pairs of Zabbix servers and Zabbix proxies for active checks.
#       If port is not specified, default port is used.
#       IPv6 addresses must be enclosed in square brackets if port for that host is specified.
#       If port is not specified, square brackets for IPv6 addresses are optional.
#       If this parameter is not specified, active checks are disabled.
#       Example: ServerActive=127.0.0.1:20051,zabbix.domain,[::1]:30051,::1,[12fc::1]
#
# Mandatory: no
# Default:
# ServerActive=

ServerActive=127.0.0.1

### Option: Hostname
#       List of comma delimited unique, case sensitive hostnames.
#       Required for active checks and must match hostnames as configured on the server.
#       Value is acquired from HostnameItem if undefined.
#
# Mandatory: no
# Default:
# Hostname=

Hostname=Zabbix server

### Option: HostnameItem
#       Item used for generating Hostname if it is undefined. Ignored if Hostname is defined.
#       Does not support UserParameters or aliases.
#
# Mandatory: no
# Default:
# HostnameItem=system.hostname

### Option: HostMetadata
#       Optional parameter that defines host metadata.
#       Host metadata is used at host auto-registration process.
#       An agent will issue an error and not start if the value is over limit of 255 characters.
#       If not defined, value will be acquired from HostMetadataItem.
#
# Mandatory: no
# Range: 0-255 characters
# Default:
# HostMetadata=

### Option: HostMetadataItem
#       Optional parameter that defines an item used for getting host metadata.
#       Host metadata is used at host auto-registration process.
#       During an auto-registration request an agent will log a warning message if
#       the value returned by specified item is over limit of 255 characters.
#       This option is only used when HostMetadata is not defined.
#
# Mandatory: no
# Default:
# HostMetadataItem=

### Option: HostInterface
#       Optional parameter that defines host interface.
#       Host interface is used at host auto-registration process.
#       An agent will issue an error and not start if the value is over limit of 255 characters.
#       If not defined, value will be acquired from HostInterfaceItem.
#
# Mandatory: no
# Range: 0-255 characters
# Default:
# HostInterface=

### Option: HostInterfaceItem
#       Optional parameter that defines an item used for getting host interface.
#       Host interface is used at host auto-registration process.
#       During an auto-registration request an agent will log a warning message if
#       the value returned by specified item is over limit of 255 characters.
#       This option is only used when HostInterface is not defined.
#
# Mandatory: no
# Default:
# HostInterfaceItem=

### Option: RefreshActiveChecks
#       How often list of active checks is refreshed, in seconds.
#
# Mandatory: no
# Range: 60-3600
# Default:
# RefreshActiveChecks=120

### Option: BufferSend
#       Do not keep data longer than N seconds in buffer.
#
# Mandatory: no
# Range: 1-3600
# Default:
# BufferSend=5

### Option: BufferSize
#       Maximum number of values in a memory buffer. The agent will send
#       all collected data to Zabbix Server or Proxy if the buffer is full.
#
# Mandatory: no
# Range: 2-65535
# Default:
# BufferSize=100

### Option: MaxLinesPerSecond
#       Maximum number of new lines the agent will send per second to Zabbix Server
#       or Proxy processing 'log' and 'logrt' active checks.
#       The provided value will be overridden by the parameter 'maxlines',
#       provided in 'log' or 'logrt' item keys.
#
# Mandatory: no
# Range: 1-1000
# Default:
# MaxLinesPerSecond=20

############ ADVANCED PARAMETERS #################

### Option: Alias
#       Sets an alias for an item key. It can be used to substitute long and complex item key with a smaller and simpler one.
#       Multiple Alias parameters may be present. Multiple parameters with the same Alias key are not allowed.
#       Different Alias keys may reference the same item key.
#       For example, to retrieve the ID of user 'zabbix':
#       Alias=zabbix.userid:vfs.file.regexp[/etc/passwd,^zabbix:.:([0-9]+),,,,\1]
#       Now shorthand key zabbix.userid may be used to retrieve data.
#       Aliases can be used in HostMetadataItem but not in HostnameItem parameters.
#
# Mandatory: no
# Range:
# Default:

### Option: Timeout
#       Spend no more than Timeout seconds on processing
#
# Mandatory: no
# Range: 1-30
# Default:
# Timeout=3

### Option: AllowRoot
#       Allow the agent to run as 'root'. If disabled and the agent is started by 'root', the agent
#       will try to switch to the user specified by the User configuration option instead.
#       Has no effect if started under a regular user.
#       0 - do not allow
#       1 - allow
#
# Mandatory: no
# Default:
# AllowRoot=0

### Option: User
#       Drop privileges to a specific, existing user on the system.
#       Only has effect if run as 'root' and AllowRoot is disabled.
#
# Mandatory: no
# Default:
# User=zabbix
# NOTE: This option is overriden by settings in systemd service file!

### Option: Include
#       You may include individual files or all files in a directory in the configuration file.
#       Installing Zabbix will create include directory in /usr/local/etc, unless modified during the compile time.
#
# Mandatory: no
# Default:
# Include=

Include=/etc/zabbix/zabbix_agentd.d/*.conf

# Include=/usr/local/etc/zabbix_agentd.userparams.conf
# Include=/usr/local/etc/zabbix_agentd.conf.d/
# Include=/usr/local/etc/zabbix_agentd.conf.d/*.conf

####### USER-DEFINED MONITORED PARAMETERS #######

### Option: UnsafeUserParameters
#       Allow all characters to be passed in arguments to user-defined parameters.
#       The following characters are not allowed:
#       \ ' " ` * ? [ ] { } ~ $ ! & ; ( ) < > | # @
#       Additionally, newline characters are not allowed.
#       0 - do not allow
#       1 - allow
#
# Mandatory: no
# Range: 0-1
# Default:
# UnsafeUserParameters=0

### Option: UserParameter
#       User-defined parameter to monitor. There can be several user-defined parameters.
#       Format: UserParameter=<key>,<shell command>
#       See 'zabbix_agentd' directory for examples.
#
# Mandatory: no
# Default:
# UserParameter=

### Option: UserParameterDir
#       Directory to execute UserParameter commands from. Only one entry is allowed.
#       When executing UserParameter commands the agent will change the working directory to the one
#       specified in the UserParameterDir option.
#       This way UserParameter commands can be specified using the relative ./ prefix.
#
# Mandatory: no
# Default:
# UserParameterDir=

####### LOADABLE MODULES #######

### Option: LoadModulePath
#       Full path to location of agent modules.
#       Default depends on compilation options.
#       To see the default path run command "zabbix_agentd --help".
#
# Mandatory: no
# Default:
# LoadModulePath=${libdir}/modules

### Option: LoadModule
#       Module to load at agent startup. Modules are used to extend functionality of the agent.
#       Formats:
#               LoadModule=<module.so>
#               LoadModule=<path/module.so>
#               LoadModule=</abs_path/module.so>
#       Either the module must be located in directory specified by LoadModulePath or the path must precede the module name.
#       If the preceding path is absolute (starts with '/') then LoadModulePath is ignored.
#       It is allowed to include multiple LoadModule parameters.
#
# Mandatory: no
# Default:
# LoadModule=

####### TLS-RELATED PARAMETERS #######

### Option: TLSConnect
#       How the agent should connect to server or proxy. Used for active checks.
#       Only one value can be specified:
#               unencrypted - connect without encryption
#               psk         - connect using TLS and a pre-shared key
#               cert        - connect using TLS and a certificate
#
# Mandatory: yes, if TLS certificate or PSK parameters are defined (even for 'unencrypted' connection)
# Default:
# TLSConnect=unencrypted

### Option: TLSAccept
#       What incoming connections to accept.
#       Multiple values can be specified, separated by comma:
#               unencrypted - accept connections without encryption
#               psk         - accept connections secured with TLS and a pre-shared key
#               cert        - accept connections secured with TLS and a certificate
#
# Mandatory: yes, if TLS certificate or PSK parameters are defined (even for 'unencrypted' connection)
# Default:
# TLSAccept=unencrypted

### Option: TLSCAFile
#       Full pathname of a file containing the top-level CA(s) certificates for
#       peer certificate verification.
#
# Mandatory: no
# Default:
# TLSCAFile=

### Option: TLSCRLFile
#       Full pathname of a file containing revoked certificates.
#
# Mandatory: no
# Default:
# TLSCRLFile=

### Option: TLSServerCertIssuer
#               Allowed server certificate issuer.
#
# Mandatory: no
# Default:
# TLSServerCertIssuer=

### Option: TLSServerCertSubject
#               Allowed server certificate subject.
#
# Mandatory: no
# Default:
# TLSServerCertSubject=

### Option: TLSCertFile
#       Full pathname of a file containing the agent certificate or certificate chain.
#
# Mandatory: no
# Default:
# TLSCertFile=

### Option: TLSKeyFile
#       Full pathname of a file containing the agent private key.
#
# Mandatory: no
# Default:
# TLSKeyFile=

### Option: TLSPSKIdentity
#       Unique, case sensitive string used to identify the pre-shared key.
#
# Mandatory: no
# Default:
# TLSPSKIdentity=

### Option: TLSPSKFile
#       Full pathname of a file containing the pre-shared key.
#
# Mandatory: no
# Default:
# TLSPSKFile=

####### For advanced users - TLS ciphersuite selection criteria #######

### Option: TLSCipherCert13
#       Cipher string for OpenSSL 1.1.1 or newer in TLS 1.3.
#       Override the default ciphersuite selection criteria for certificate-based encryption.
#
# Mandatory: no
# Default:
# TLSCipherCert13=

### Option: TLSCipherCert
#       GnuTLS priority string or OpenSSL (TLS 1.2) cipher string.
#       Override the default ciphersuite selection criteria for certificate-based encryption.
#       Example for GnuTLS:
#               NONE:+VERS-TLS1.2:+ECDHE-RSA:+RSA:+AES-128-GCM:+AES-128-CBC:+AEAD:+SHA256:+SHA1:+CURVE-ALL:+COMP-NULL:+SIGN-ALL:+CTYPE-X.509
#       Example for OpenSSL:
#               EECDH+aRSA+AES128:RSA+aRSA+AES128
#
# Mandatory: no
# Default:
# TLSCipherCert=

### Option: TLSCipherPSK13
#       Cipher string for OpenSSL 1.1.1 or newer in TLS 1.3.
#       Override the default ciphersuite selection criteria for PSK-based encryption.
#       Example:
#               TLS_CHACHA20_POLY1305_SHA256:TLS_AES_128_GCM_SHA256
#
# Mandatory: no
# Default:
# TLSCipherPSK13=

### Option: TLSCipherPSK
#       GnuTLS priority string or OpenSSL (TLS 1.2) cipher string.
#       Override the default ciphersuite selection criteria for PSK-based encryption.
#       Example for GnuTLS:
#               NONE:+VERS-TLS1.2:+ECDHE-PSK:+PSK:+AES-128-GCM:+AES-128-CBC:+AEAD:+SHA256:+SHA1:+CURVE-ALL:+COMP-NULL:+SIGN-ALL
#       Example for OpenSSL:
#               kECDHEPSK+AES128:kPSK+AES128
#
# Mandatory: no
# Default:
# TLSCipherPSK=

### Option: TLSCipherAll13
#       Cipher string for OpenSSL 1.1.1 or newer in TLS 1.3.
#       Override the default ciphersuite selection criteria for certificate- and PSK-based encryption.
#       Example:
#               TLS_AES_256_GCM_SHA384:TLS_CHACHA20_POLY1305_SHA256:TLS_AES_128_GCM_SHA256
#
# Mandatory: no
# Default:
# TLSCipherAll13=

### Option: TLSCipherAll
#       GnuTLS priority string or OpenSSL (TLS 1.2) cipher string.
#       Override the default ciphersuite selection criteria for certificate- and PSK-based encryption.
#       Example for GnuTLS:
#               NONE:+VERS-TLS1.2:+ECDHE-RSA:+RSA:+ECDHE-PSK:+PSK:+AES-128-GCM:+AES-128-CBC:+AEAD:+SHA256:+SHA1:+CURVE-ALL:+COMP-NULL:+SIGN-ALL:+CTYPE-X.509
#       Example for OpenSSL:
#               EECDH+aRSA+AES128:RSA+aRSA+AES128:kECDHEPSK+AES128:kPSK+AES128
#
# Mandatory: no
# Default:
# TLSCipherAll=