PowerEdge：如何在 Red Hat Linux 系統中部署網路服務

Summary: 本指南說明如何在 Red Hat Linux 系統中部署網路服務。

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Instructions

在某些情況下，網路服務必須部署在 Red Hat Linux 系統中。例如，DNS、DHCP、NTP、FTP、HTTP、EMail 服務等。

本文在下面共用部署這些網路服務的摘要步驟。

步驟摘要

搜尋與安裝服務（yum/rpm）
啟動並啟用服務（systemctl）
防火牆允許服務（firewall-cmd）
在首次備份預設配置檔（*.conf、*.cnf、*.cfg 等）後搜索和修改服務配置檔使用“man”查找説明和示例。使用「vim」編輯組態檔案檢查語法。
檢閱並設定檔案權限和安全性原則（chmod/chown/setfacl/selinux）
重新啟動服務並進行故障排除（如果無法重新啟動服務）
測試並驗證服務狀態（確保結果符合預期）

有關動態主機配置通訊協定（DHCP）服務的更多具體範例如下。

DHCP 服務上特定命令的摘要步驟

搜尋並安裝 DHCP 服務

[root@servera ~]# yum search dhcp*
Last metadata expiration check: 0:13:07 ago on Thu 18 May 2023 06:54:40 AM GMT.
============================================================== Name Matched: dhcp* ===============================================================

dhcp-libs.x86_64 : Shared libraries used by ISC dhcp client and server
dhcp-libs.i686 : Shared libraries used by ISC dhcp client and server
dhcp-libs.x86_64 : Shared libraries used by ISC dhcp client and server
dhcp-relay.x86_64 : Provides the ISC DHCP relay agent
dhcp-client.x86_64 : Provides the ISC DHCP client daemon and dhclient-script
dhcp-common.noarch : Common files used by ISC dhcp client, server and relay agent
dhcp-client.x86_64 : Provides the ISC DHCP client daemon and dhclient-script
dhcp-common.noarch : Common files used by ISC dhcp client, server and relay agent
dhcp-server.x86_64 : Provides the ISC DHCP server      <-- this is the dhcp service installation package 
[root@servera ~]#

[root@servera ~]# yum list dhcp-server
Last metadata expiration check: 0:15:12 ago on Thu 18 May 2023 06:54:40 AM GMT.
Available Packages      <-- this package is available, if it shows "Installed Packages", means the service already installed
dhcp-server.x86_64                 12:4.3.6-34.el8                 rhel-8.1-for-x86_64-baseos-rpms
[root@servera ~]#

[root@servera ~]# yum provides dhcp-server
Last metadata expiration check: 0:17:31 ago on Thu 18 May 2023 06:54:40 AM GMT.
dhcp-server-12:4.3.6-34.el8.x86_64 : Provides the ISC DHCP server
Repo        : rhel-8.1-for-x86_64-baseos-rpms      <-- this is the yum repository that provide the service package 
Matched from:
Provide    : dhcp-server = 12:4.3.6-34.el8
[root@servera ~]#

[root@servera ~]# yum -y install dhcp-server
Last metadata expiration check: 0:20:30 ago on Thu 18 May 2023 06:54:40 AM GMT.
Dependencies resolved.
==============================================================================
 Package                       Architecture             Version                           Repository                                         Size
==============================================================================
Installing:
 dhcp-server                   x86_64                   12:4.3.6-34.el8                   rhel-8.1-for-x86_64-baseos-rpms                   530 k
Transaction Summary
==============================================================================
Install  1 Package
Total download size: 530 k
Installed size: 1.3 M
Downloading Packages:
dhcp-server-4.3.6-34.el8.x86_64.rpm                                                                               5.6 MB/s | 530 kB     00:00    
-----------------------------------------------------------------------------------------------------------------------------------------------
Total                                                                                                             5.3 MB/s | 530 kB     00:00     
Running transaction check
Transaction check succeeded.
Running transaction test
Transaction test succeeded.
Running transaction
  Preparing        :                                                                                                                          1/1 
  Running scriptlet: dhcp-server-12:4.3.6-34.el8.x86_64                                                                                       1/1 
  Installing       : dhcp-server-12:4.3.6-34.el8.x86_64                                                                                       1/1 
  Running scriptlet: dhcp-server-12:4.3.6-34.el8.x86_64                                                                                       1/1 
  Verifying        : dhcp-server-12:4.3.6-34.el8.x86_64                                                                                       1/1 
Installed:
  dhcp-server-12:4.3.6-34.el8.x86_64                                                                                                              
Complete!
[root@servera ~]#

啟動並啟用 DHCP 服務

[root@servera ~]# rpm -ql dhcp-server | grep .service
/usr/lib/systemd/system/dhcpd.service      <-- find out the service name after installation
/usr/lib/systemd/system/dhcpd6.service
[root@servera ~]#

[root@servera ~]# systemctl list-unit-files | grep dhcp
dhcpd.service                              disabled      <-- service disable by default
dhcpd6.service                             disabled       
[root@servera ~]#

[root@servera ~]# systemctl enable --now dhcpd      <-- start and enable dhcp service
Created symlink /etc/systemd/system/multi-user.target.wants/dhcpd.service → /usr/lib/systemd/system/dhcpd.service.
Job for dhcpd.service failed because the control process exited with error code.
See "systemctl status dhcpd.service" and "journalctl -xe" for details.
[root@servera ~]#

[root@servera ~]# systemctl status dhcpd      <-- check dhcp service status 
● dhcpd.service - DHCPv4 Server Daemon
   Loaded: loaded (/usr/lib/systemd/system/dhcpd.service; enabled; vendor preset: disabled)      <-- service enabled 
   Active: failed (Result: exit-code) since Thu 2023-05-18 07:24:16 GMT; 56s ago      <-- status is failed (Result: exit-code)
     Docs: man:dhcpd(8)      <-- you can get help from here, by "man dhcpd" and "man dhcpd.conf"
           man:dhcpd.conf(5)
  Process: 3963 ExecStart=/usr/sbin/dhcpd -f -cf /etc/dhcp/dhcpd.conf -user dhcpd -group dhcpd --no-pid $DHCPDARGS (code=exited, status=1/FAILURE)      <-- showed mistakes why failure
 Main PID: 3963 (code=exited, status=1/FAILURE)
May 18 07:24:16 servera dhcpd[3963]: have been made to the base software release in order to make
May 18 07:24:16 servera dhcpd[3963]: it work better with this distribution.
May 18 07:24:16 servera dhcpd[3963]: 
May 18 07:24:16 servera dhcpd[3963]: Please report issues with this software via:
May 18 07:24:16 servera dhcpd[3963]: bugzilla-redhat-com
May 18 07:24:16 servera dhcpd[3963]: 
May 18 07:24:16 servera dhcpd[3963]: exiting.
May 18 07:24:16 servera systemd[1]: dhcpd.service: Main process exited, code=exited, status=1/FAILURE
May 18 07:24:16 servera systemd[1]: dhcpd.service: Failed with result 'exit-code'.
May 18 07:24:16 servera systemd[1]: Failed to start DHCPv4 Server Daemon.
[root@servera ~]#

防火牆許可服務

[root@servera ~]# firewall-cmd --permanent --add-service=dhcp
success
[root@servera ~]# 

[root@servera ~]# firewall-cmd --reload 
success
[root@servera ~]# 

[root@servera ~]# firewall-cmd --list-all
public (active)
  target: default
  icmp-block-inversion: no
  interfaces: eth0 eth1
  sources: 
  services: cockpit dhcp dhcpv6-client ssh
  ports: 
  protocols: 
  masquerade: no
  forward-ports: 
  source-ports: 
  icmp-blocks: 
  rich rules: 
[root@servera ~]#

搜尋與修改服務設定檔

[root@servera ~]# rpm -qc dhcp-server
/etc/dhcp/dhcpd.conf      <-- this is the main configuration file
/etc/dhcp/dhcpd6.conf
/etc/openldap/schema/dhcp.schema
/etc/sysconfig/dhcpd      <-- this is another configuration file should review
/var/lib/dhcpd/dhcpd.leases
/var/lib/dhcpd/dhcpd6.leases
[root@servera ~]#

[root@servera ~]# cat /etc/dhcp/dhcpd.conf
#
# DHCP Server Configuration file.
#   see /usr/share/doc/dhcp-server/dhcpd.conf.example      <-- this is configuration example
#   see dhcpd.conf(5) man page
#
[root@servera ~]#

[root@servera ~]# cp /etc/dhcp/dhcpd.conf /etc/dhcp/dhcpd.conf.bak      <-- backup main configuration
[root@servera ~]# 

[root@servera ~]# vim /etc/dhcp/dhcpd.conf      <-- edit the main configuration file 
:r /usr/share/doc/dhcp-server/dhcpd.conf.example      <-- read and copy example to this main configuration file
Then make changes, get following result finally : 
#
# dhcpd.conf
#
option domain-name "example-net";
option domain-name-servers 172.25.254.254;
default-lease-time 800;
max-lease-time 7200;
authoritative;
log-facility local7;
subnet 192.168.0.0 netmask 255.255.255.0 {
  range 192.168.0.200 192.168.0.254;
  option domain-name-servers 172.25.254.254;
  option domain-name "example-net";
  option routers 192.168.0.1;
  option broadcast-address 192.168.0.255;
  default-lease-time 800;
  max-lease-time 7200;
}
# assign one specific ip address to host serverb
host serverb {
  hardware ethernet 52:54:00:01:fa:0b;
  fixed-address 192.168.0.102;
}

[root@servera ~]# cat /etc/sysconfig/dhcpd
# WARNING: This file is NOT used anymore.
# If you are here to restrict what interfaces should dhcpd listen on,
# be aware that dhcpd listens *only* on interfaces for which it finds subnet
# declaration in dhcpd.conf. It means that explicitly enumerating interfaces
# also on command line should not be required in most cases.
# If you still insist on adding some command line options,
# copy dhcpd.service from /lib/systemd/system to /etc/systemd/system and modify
# it there.
# example:      <-- follow above guide to set dhcp running interface
# $ cp /usr/lib/systemd/system/dhcpd.service /etc/systemd/system/
# $ vi /etc/systemd/system/dhcpd.service
# $ ExecStart=/usr/sbin/dhcpd -f -cf /etc/dhcp/dhcpd.conf -user dhcpd -group dhcpd --no-pid <your_interface_name(s)>
# $ systemctl --system daemon-reload
# $ systemctl restart dhcpd.service
[root@servera ~]#

[root@servera ~]# vi /etc/systemd/system/dhcpd.service
...
[Service]
...
ExecStart=/usr/sbin/dhcpd -f -cf /etc/dhcp/dhcpd.conf -user dhcpd -group dhcpd --no-pid eth1      <-- set interface "eth1"
...
[root@servera ~]# dhcpd -t      <-- syntax check after configuration file modified
Internet Systems Consortium DHCP Server 4.3.6
Copyright 2004-2017 Internet Systems Consortium.
All rights reserved.
For info, please visit www-isc-org/software/dhcp/
ldap_gssapi_principal is not set,GSSAPI Authentication for LDAP will not be used
Not searching LDAP since ldap-server, ldap-port and ldap-base-dn were not specified in the config file
Config file: /etc/dhcp/dhcpd.conf
Database file: /var/lib/dhcpd/dhcpd.leases
PID file: /var/run/dhcpd.pid
Source compiled to use binary-leases
[root@servera ~]# 

[root@servera ~]# echo $?
0      <-- it means there's no errors, all fine for syntax check by command "dhcpd -t"
[root@servera ~]#

檢視並設定檔案權限和安全性原則

關於文件許可權和安全策略，您不需要對 DHCP 服務進行任何更改。如果您對此有任何特定要求，請根據您的設計進行更改。

重新啟動服務

[root@servera ~]# systemctl --system daemon-reload
[root@servera ~]# 

[root@servera ~]# systemctl restart dhcpd.service
[root@servera ~]# 

[root@servera ~]# systemctl status dhcpd
● dhcpd.service - DHCPv4 Server Daemon
   Loaded: loaded (/etc/systemd/system/dhcpd.service; enabled; vendor preset: disabled)
   Active: active (running) since Thu 2023-05-18 08:00:00 GMT; 16s ago      <-- status is active (running)
     Docs: man:dhcpd(8)
           man:dhcpd.conf(5)
 Main PID: 4514 (dhcpd)
   Status: "Dispatching packets..."
    Tasks: 1 (limit: 11251)
   Memory: 5.2M
   CGroup: /system.slice/dhcpd.service
           └─4514 /usr/sbin/dhcpd -f -cf /etc/dhcp/dhcpd.conf -user dhcpd -group dhcpd --no-pid eth1

May 18 08:00:00 servera systemd[1]: Started DHCPv4 Server Daemon.
May 18 08:00:12 servera dhcpd[4514]: DHCPDISCOVER from 52:54:00:01:fa:0d via eth1
May 18 08:00:12 servera dhcpd[4514]: DHCPDISCOVER from 52:54:00:02:fa:0d via eth1
May 18 08:00:13 servera dhcpd[4514]: DHCPOFFER on 192.168.0.200 to 52:54:00:01:fa:0d (serverd) via eth1
May 18 08:00:13 servera dhcpd[4514]: DHCPREQUEST for 192.168.0.200 (192.168.0.10) from 52:54:00:01:fa:0d (serverd) via eth1
May 18 08:00:13 servera dhcpd[4514]: DHCPACK on 192.168.0.200 to 52:54:00:01:fa:0d (serverd) via eth1
May 18 08:00:13 servera dhcpd[4514]: ICMP Echo Reply for 192.168.0.200 late or spurious.
May 18 08:00:13 servera dhcpd[4514]: DHCPOFFER on 192.168.0.201 to 52:54:00:02:fa:0d (serverd) via eth1
May 18 08:00:13 servera dhcpd[4514]: DHCPREQUEST for 192.168.0.201 (192.168.0.10) from 52:54:00:02:fa:0d (serverd) via eth1
May 18 08:00:13 servera dhcpd[4514]: DHCPACK on 192.168.0.201 to 52:54:00:02:fa:0d (serverd) via eth1
[root@servera ~]#

Notes: 
If service fails to restart, you should do further trouble-shooting to resolve it. 
From the below logs, you may find some valuable clues. 
[root@server ~]# tail /var/log/messages
[root@server ~]# journalctl -u [service unit name]

測試並驗證服務狀態

From another host serverb to check if dhcp service working fine. 
[root@serverb ~]# nmcli connection show | grep eth1
Wired connection 2  706e063c-ee02-349e-8311-2c9837611ec4  ethernet  eth1   
[root@serverb ~]#

[root@serverb ~]# nmcli connection modify Wired\ connection\ 2 ipv4.method auto connection.autoconnect yes
[root@serverb ~]# 

[root@serverb ~]# nmcli connection up Wired\ connection\ 2
Connection successfully activated (D-Bus active path: /org/freedesktop/NetworkManager/ActiveConnection/260)
[root@serverb ~]# 

[root@serverb ~]# ip address show eth1
3: eth1: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel state UP group default qlen 1000
    link/ether 52:54:00:01:fa:0b brd ff:ff:ff:ff:ff:ff
    inet 192.168.0.102/24 brd 192.168.0.255 scope global dynamic noprefixroute eth1
       valid_lft 777sec preferred_lft 777sec
    inet6 fe80::dead:38b9:8837:8c6e/64 scope link noprefixroute 
       valid_lft forever preferred_lft forever
[root@serverb ~]#

[root@serverb ~]# ping 192.168.0.10      <-- servera is reachable
PING 192.168.0.10 (192.168.0.10) 56(84) bytes of data.
64 bytes from 192.168.0.10: icmp_seq=1 ttl=64 time=3.21 ms
64 bytes from 192.168.0.10: icmp_seq=2 ttl=64 time=1.64 ms
64 bytes from 192.168.0.10: icmp_seq=3 ttl=64 time=1.19 ms
^C
--- 192.168.0.10 ping statistics ---
3 packets transmitted, 3 received, 0% packet loss, time 10ms
rtt min/avg/max/mdev = 1.189/2.013/3.210/0.867 ms
[root@serverb ~]#

[root@servera ~]# ip address show eth1
3: eth1: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel state UP group default qlen 1000
    link/ether 52:54:00:01:fa:0a brd ff:ff:ff:ff:ff:ff
    inet 192.168.0.10/24 brd 192.168.0.255 scope global noprefixroute eth1
       valid_lft forever preferred_lft forever
    inet6 fe80::8779:8d69:d3cf:3fab/64 scope link noprefixroute 
       valid_lft forever preferred_lft forever
[root@servera ~]#

以下是一些已知的服務名稱表清單：

圖 1：服務名稱表清單

注意：本文中的所有記錄均來自 VMware 環境中的本機虛擬實驗室。

Affected Products

Red Hat Enterprise Linux Version 8

Article Number: 000213739

Article Type: How To

Last Modified: 14 Aug 2024

Version: 4

Check if your device is covered by Support Services.

PowerEdge：如何在 Red Hat Linux 系統中部署網路服務

Summary: 本指南說明如何在 Red Hat Linux 系統中部署網路服務。

Instructions

步驟摘要

DHCP 服務上特定命令的摘要步驟

以下是一些已知的服務名稱表清單：

Affected Products

Article Properties

Find answers to your questions from other Dell users

Support Services

Article Properties

Find answers to your questions from other Dell users

Support Services

PowerEdge：如何在 Red Hat Linux 系統中部署網路服務

Summary: 本指南說明如何在 Red Hat Linux 系統中部署網路服務。

Detailed Article

Instructions

Affected Products

Instructions

步驟摘要

DHCP 服務上特定命令的摘要步驟

以下是一些已知的服務名稱表清單：

Affected Products

Article Properties

Find answers to your questions from other Dell users

Support Services

Article Properties

Find answers to your questions from other Dell users

Support Services