System Administration - Fedora

Table of Contents

• Table of Contents
• Service Management
  • Setup SSH Server
• Software Management
  • yum
  • yum proxy
  • history
• Networking
  • Static IP
    • Without NetworkManager
    • Using Network Manager
  • Create Multiple IP Addresses to One Single Network Interface
• System Maintainance
  • Gen Password
  • System Backup
  • Release Upgrade
• screen dump and view
• systemd
  • Type
  • Example
  • Reload
  • Power Management
  • Target(Runlevel)
  • journalctl
    • Configure
  • core dump
• References

Service Management

Setup SSH Server

1. install openssh-server

   yum install openssh-server
   

2. verify if openssh-server is installed

   rpm -qa | grep openssh-server
   

3. modifying ssh configure files (optional)

   there are a lot of configure options in the configure file /etc/ssh/ssh_config, most of them are commented out

   #Port 22
   #Protocol 2,1    
   #PermitRootLogin yes
   

4. open the TCP port 22 if the firewall is active

   iptables -I INPUT -p tcp --dport 22 -j ACCEPT
   

5. auto start when booting

   sudo systemctl enable sshd.service
   

Software Management

yum

• 使用yum解决依赖关系来安装你硬盘上的rpm包 yum localinstall 程序名称
• 查找程序的信息 yum info 程序名称
• 启用源 yum –enablerepo=repo_name
• 禁用源 yum –disablerepo=repo_name
• 导入 fedora GPG 钥 fedora有两个名叫”fedora”和”updates”的基本源.为了使用他们并不获得未标记的软件包的误信息,你必需导入它们的GPG钥.输入: rpm –import /etc/pki/rpm-gpg/*

• 现在我们就安装livna的源,一个提供了很多多媒体解码器和额外软件的第三方的源.

  在接下来的文章中,我会认为你已经安装好了livna的源.输入:

  rpm -hiv http://rpm.livna.org/livna-release-9.rpm

  rpm –import http://rpm.livna.org/RPM-LIVNA-GPG-KEY

yum proxy

/etc/yum.conf

在 yum 的配置中添加如下行:

Proxy=http://ip:port/

Proxy 代表 proxy 的 ip, port 代表代理监听的端口. 别忘了端口后的 /.

history

yum history list all
for i in {2..19}; do
	yum history info "$i"
done > install.log

Networking

Static IP

Without NetworkManager

/etc/sysconfig/network-scripts/ifcfg-enp0s3

HWADDR="00:11:22:33:44:55"
TYPE="Ethernet"
BOOTPROTO="static"
IPADDR=192.168.249.108
NETMASK=255.255.255.0
NM_CONTROLLED=no
DEFROUTE="yes"
PEERDNS="yes"
PEERROUTES="yes"
IPV4_FAILURE_FATAL="no"
IPV6INIT="yes"
IPV6_AUTOCONF="yes"
IPV6_DEFROUTE="yes"
IPV6_PEERDNS="yes"
IPV6_PEERROUTES="yes"
IPV6_FAILURE_FATAL="no"
NAME="enp0s3"
UUID="00000000-0000-0000-0000-000000000000"
ONBOOT="yes"

# reload network service
systemctl restart network.service
# verify addr
ip addr

Using Network Manager

NM_CONTROLLED=yes

Use nmcli to config and reload network service via systemd.

Create Multiple IP Addresses to One Single Network Interface

1. 我们先打开网络接口的文件

   sudo gedit /etc/network/interfaces
   

2. 照上边 eth0 添加

   eth0:0
   auto eth0
   iface eth0 inet static
   name Ethernet Lan card
   address 192.168.1.1
   netmask 255.255.255.0
   network 192.168.1.0
   broadcast 192.168.1.255
   gateway 192.168.1.1
   auto eth0:0
   iface eth0:0 inet static
   name Ethernet
   address 192.168.1.2
   netmask 255.255.255.0
   network 192.168.1.0
   broadcast 192.168.1.255
   gateway 192.168.1.1
   

3. 重启服务

   sudo /etc/init.d/networking restart
   

4. 测试新的ip地址是否生效

   ping 192.168.0.1
   ping 192.168.0.2
   

System Maintainance

Gen Password

openssl rand -base64 14

System Backup

sudo su
cd /
tar -cvpzf /media/sda7/backup.tgz \
        --exclude=/proc \
        --exclude=/lost+found \
        --exclude=/mnt \
        --exclude=/sys \
        --exclude=/media /

Release Upgrade

dnf update --refresh
dnf install dnf-plugin-system-upgrade
dnf system-upgrade download --refresh --releasever=24
dnf system-upgrade reboot

screen dump and view

# dump
xwd-display localhost:0 -root  > screen.xwd
# view
xwud -in screen.xwd

systemd

• service.service
• socket.socket
• device.device
• mount.mount,
• automount.automount
• swap.swap
• target.target
• path.path
• timer.timer
• snapshot.snapshot
• slice.slice
• scope.scope

See man systemd.unit for more information.

使用 systemctl 控制单元时，通常需要使用单元文件的全名，包括扩展名（例如 sshd.service）。但是有些单元可以在systemctl中使用简写方式。

如果无扩展名，systemctl 默认把扩展名当作 .service。例如 netcfg 和 netcfg.service 是等价的。 挂载点会自动转化为相应的 .mount 单元。例如 /home 等价于 home.mount。 设备会自动转化为相应的 .device 单元，所以 /dev/sda2 等价于 dev-sda2.device。

所有可用的单元文件存放在 /usr/lib/systemd/system/ 和 /etc/systemd/system/ 目录（后者优先级更高）。

在 systemctl 参数中添加 -H <user>@<host> 可以实现对其他机器的远程控制。该过程使用 SSH 链接。

systemctl is equivalent to systemctl list-units

# list failed units
systemctl --failed
# list unit files
systemctl list-unit-files
# prevent a service from starting dynamically or even manually unless unmasked
systemctl mask foo

Type

• Type=simple(default)

  systemd认为该服务将立即启动。服务进程不会fork。如果该服务要启动其他服务，不要使用此类型启动，除非该服务是socket激活型。

• Type=forking

  systemd认为当该服务进程fork，且父进程退出后服务启动成功。对于常规的守护进程（daemon），除非你确定此启动方式无法满足需求，使用此类型启动即可。使用此启动类型应同时指定 PIDFile=，以便systemd能够跟踪服务的主进程。

• Type=oneshot

  这一选项适用于只执行一项任务、随后立即退出的服务。可能需要同时设置 RemainAfterExit=yes 使得 systemd 在服务进程退出之后仍然认为服务处于激活状态。

• Type=notify

  与 Type=simple 相同，但约定服务会在就绪后向 systemd 发送一个信号。这一通知的实现由 libsystemd-daemon.so 提供。

• Type=dbus

  若以此方式启动，当指定的 BusName 出现在DBus系统总线上时，systemd认为服务就绪。

Example

view configure file

$ systemctl cat sshd.service
[Unit]
Description=OpenSSH server daemon
Documentation=man:sshd(8) man:sshd_config(5)
After=network.target sshd-keygen.service
Wants=sshd-keygen.service

[Service]
EnvironmentFile=/etc/sysconfig/sshd
ExecStart=/usr/sbin/sshd -D $OPTIONS
ExecReload=/bin/kill -HUP $MAINPID
Type=simple
KillMode=process
Restart=on-failure
RestartSec=42s

[Install]
WantedBy=multi-user.target

Reload

systemctl daemon-reload
systemctl restart <unitname>
systemctl restart NetworkManager
systemctl stop httpd.service
# reload configuration
systemctl reload httpd.service
systemctl try-restart httpd.service
# kill when stop not working
systemctl kill httpd.service
# show help manual in unit file
systemctl help <unit>

Power Management

systemctl reboot
systemctl poweroff
systemctl suspend
systemctl hibernate
systemctl hybrid-sleep

Target(Runlevel)

systemctl list-units --type=target
# telinit 5
systemctl isolate graphical.target
# modify default target
systemctl enable multi-user.target

journalctl

# like tail -f
journalctl -f
# show specific program
journalctl /usr/lib/systemd/systemd
# show specific PID
journalctl _PID=1
# show specific unit
journalctl -u netcfg

for more information:

• man journalctl
• man systemd.journal-fields

Configure

/etc/systemd/journald.conf

SystemMaxUse=50M

core dump

/etc/sysctl.d/49-coredump.conf

kernel.core_pattern = core
kernel.core_uses_pid = 0

to activate conf:

/usr/lib/systemd/systemd-sysctl
# may need unlimit too
ulimit -c unlimited

References

• DNF system upgrade
• fedora: Systemd
• Create Multiple IP Addresses to One Single Network Interface