總結(jié)
1、ubuntu修改服務(wù)器名重啟后生效的方法是直接修改/etc/hostname文件
2、ubuntu 22.04操作系統(tǒng)配置ip和dns信息，一般只需要使用netplan命令行工具來配置就行，在/etc/netplan/在目錄下創(chuàng)建一個yaml文件就可以實現(xiàn)ip和dns的配置，當(dāng)然如果/etc/netplan下有多個yaml文件，則所有/etc/netplan/*.yaml文件都將被netplan命令行使用，參見官方文檔https://ubuntu.com/server/docs/network-configuration和https://manpages.ubuntu.com/manpages/jammy/man5/netplan.5.html
3、個人不建議使用/etc/resolve.conf來配置ubuntu 22.04操作系統(tǒng)的dns信息，因為太復(fù)雜了，這個文件是被systemd-resolved服務(wù)托管。ubuntu操作系統(tǒng)/etc/resolve.conf中默認使用的是 nameserver 127.0.0.53回環(huán)地址,/etc/resolve.conf文中有這么一句話This is /run/systemd/resolve/stub-resolv.conf managed by man:systemd-resolved(8). Do not edit。說明這個文件是被systemd-resolved這個服務(wù)托管的。通過 netstat -tnpl| grep systemd-resolved 查看到這個服務(wù)是監(jiān)聽在 53 號端口上。為啥要用127.0.0.53作為回環(huán)地址而不是127.0.0.1，因為127網(wǎng)段都是回環(huán)地址(127.0.0.1 - 127.255.255.254),不過通常用大家只喜歡用127.0.0.1來表示而已，53表示dns端口
3.1、新安裝的ubuntu 22.04環(huán)境不做其他改動的情況下，/etc/resolv.conf是/run/systemd/resolve/stub-resolv.conf的軟鏈接，如果只是手工更改/etc/resolv.conf中的內(nèi)容，重啟會后發(fā)現(xiàn)/etc/resolv.conf中的內(nèi)容又恢復(fù)成原樣了，比如注釋/etc/resolv.conf文件中的nameserver 127.0.0.53這一行，重啟系統(tǒng)后被注釋掉的nameserver 127.0.0.53這一行又回來了，如果不想重啟后/etc/resolv.conf中的內(nèi)容恢復(fù)成原樣，則執(zhí)行systemctl stop systemd-resolved和systemctl disable systemd-resolved，或把/etc/resolv.conf對應(yīng)的軟鏈接刪除，再手工建立一個/etc/resolv.conf
3.2、使用/etc/netplan/00-installer-config.yaml配置DNS 172.22.10.66并執(zhí)行netplan apply使之生效，再修改/etc/systemd/resolved.conf內(nèi)容里的DNS為172.22.136.2，然后執(zhí)行systemctl restart systemd-resolved，發(fā)現(xiàn)/etc/resolv.conf中的內(nèi)容沒變還是127.0.0.53，再執(zhí)行resolvectl status可以看到/etc/systemd/resolved.conf中的DNS 172.22.136.2存在，/etc/netplan/00-installer-config.yaml中的DNS 172.22.10.66也在，就是沒有/etc/resolv.conf中的127.0.0.53。重啟操作系統(tǒng)后/etc/resolv.conf中的內(nèi)容沒變還是127.0.0.53，重啟操作系統(tǒng)后執(zhí)行resolvectl status還是只有/etc/systemd/resolved.conf中的DNS 172.22.136.2和/etc/netplan/00-installer-config.yaml中的DNS 172.22.10.66，沒有/etc/resolv.conf中的127.0.0.53
4、ubuntu官方不建議使用/etc/resolve.conf來配置ubuntu 的dns信息，ubuntu對于/etc/resolv.conf的官方描述：If you require DNS for your temporary network configuration, you can add DNS server IP addresses in the file /etc/resolv.conf. In general, editing /etc/resolv.conf directly is not recommended, but this is a temporary and non-persistent configuration.
5、ubuntu 22.04查看dns信息的命令是resolvectl status，該命令可以看到全局dns信息和某個網(wǎng)卡的dns信息，全局DNS服務(wù)器信息一般來自配置文件/etc/systemd/resolved.conf,僅在/etc/resolv.conf不是一個指向/run/systemd/resolve/stub-resolv.conf, /usr/lib/systemd/resolv.conf, /run/systemd/resolve/resolv.conf 之一的軟連接的情況下，且/etc/systemd/resolved.conf中dns被注釋掉的情況下，全局DNS服務(wù)器才會讀取自/etc/resolv.conf，所以這就是不建議大家使用/etc/resolve.conf來配置ubuntu 的dns信息的原因。
修改服務(wù)器名
修改服務(wù)器名為FRSBachDEV3，重啟后也生效的方法
vi /etc/hostname
FRSBachDEV3
備注：如果/etc/hostname文件中的內(nèi)容寫成hostname FRSBachDEV3，那么重啟后服務(wù)器名就變成了hostnameFRSBachDEV3
修改IP
https://ubuntu.com/server/docs/network-configuration
https://manpages.ubuntu.com/manpages/jammy/man5/netplan.5.html
netplan是一個命令行工具，用于ubuntu上配置網(wǎng)絡(luò)，所有/etc/netplan/*.yaml文件都將被使用
root@FRSBachDEV3:~# cat /etc/netplan/00-installer-config.yaml
network:
ethernets:
ens160:
dhcp4: true
version: 2
root@FRSBachDEV3:~# vim /etc/netplan/00-installer-config.yaml
network:
ethernets:
ens160:
dhcp4: false
addresses: [172.22.136.147/22]
routes:
- to: default
via: 172.22.136.1
nameservers:
search: [dai.netdai.com,netdai.com]
addresses: [172.22.10.66,172.22.10.67]
version: 2
備注：
dhcp4中的4表示ipv4
gateway4中的4表示ipv4，不過gateway4已經(jīng)被廢棄，配置了gateway4再執(zhí)行netplan apply的話會報錯** (generate:1426): WARNING **: 09:54:13.918: gateway4 has been deprecated, use default routes instead.See the ‘Default routes’ section of the documentation for more details.
routes項填寫網(wǎng)關(guān)地址
addresses項填寫ip地址
nameservers項填寫dns地址或搜索域，其中addresses子項是dns地址列表，search子項是搜索域名列表
version: 2這一項表示YAML版本是2，curtin,MaaS等目前使用的YAML的版本是1
root@FRSBachDEV3:~# netplan apply
root@FRSBachDEV3:~# cat /etc/resolv.conf
nameserver 127.0.0.53
options edns0 trust-ad
search dai.netdai.com netdai.com
root@FRSBachDEV3:~# ifconfig
ens160: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500
inet 172.22.136.147 netmask 255.255.252.0 broadcast 172.22.139.255
inet6 fe80::250:56ff:fe94:522d prefixlen 64 scopeid 0x20<link>
ether 00:50:56:94:52:2d txqueuelen 1000 (Ethernet)
RX packets 45071 bytes 3394009 (3.3 MB)
RX errors 0 dropped 40 overruns 0 frame 0
TX packets 765 bytes 78732 (78.7 KB)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
lo: flags=73<UP,LOOPBACK,RUNNING> mtu 65536
inet 127.0.0.1 netmask 255.0.0.0
inet6 ::1 prefixlen 128 scopeid 0x10<host>
loop txqueuelen 1000 (Local Loopback)
RX packets 2331 bytes 168025 (168.0 KB)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 2331 bytes 168025 (168.0 KB)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
查看網(wǎng)關(guān)
root@FRSBachDEV3:~# ip route | grep default
default via 172.22.136.1 dev ens160 proto static
root@FRSBachDEV3:~# nmcli dev show|grep GATEWAY
IP4.GATEWAY: 172.22.136.1
IP6.GATEWAY: --
IP4.GATEWAY: --
IP6.GATEWAY: --
查看dns文章來源：http://www.zghlxwxcb.cn/news/detail-745822.html
root@FRSBachDEV3:~# resolvectl status
Global
Protocols: -LLMNR -mDNS -DNSOverTLS DNSSEC=no/unsupported
resolv.conf mode: stub
Link 2 (ens160)
Current Scopes: DNS
Protocols: +DefaultRoute +LLMNR -mDNS -DNSOverTLS DNSSEC=no/unsupported
Current DNS Server: 172.22.10.66
DNS Servers: 172.22.10.66 172.22.10.67
DNS Domain: dai.netdai.com netdai.com
實驗：如何才會使用到/etc/resolve.conf中的dns信息文章來源地址http://www.zghlxwxcb.cn/news/detail-745822.html
/etc/systemd/resolved.conf中dns為172.22.136.2
root@FRSBachDEV3:~# cat /etc/systemd/resolved.conf |grep DNS=
DNS=172.22.136.2
/etc/resolv.conf來自軟鏈接/run/systemd/resolve/stub-resolv.conf
root@FRSBachDEV3:~# ll /etc/resolv.conf
lrwxrwxrwx 1 root root 39 Aug 9 2022 /etc/resolv.conf -> ../run/systemd/resolve/stub-resolv.conf
root@FRSBachDEV3:~# cat /run/systemd/resolve/stub-resolv.conf
nameserver 127.0.0.53
options edns0 trust-ad
search dai.netdai.com netdai.com
/run/systemd/resolve/resolv.conf有來自/etc/systemd/resolved.conf中dns 172.22.136.2，也有來自/etc/netplan/00-installer-config.yaml中dns 172.22.10.66 172.22.10.67，就是沒有來自/etc/resolv.conf的127.0.0.53
root@FRSBachDEV3:~# cat /run/systemd/resolve/resolv.conf
nameserver 172.22.136.2
nameserver 172.22.10.66
nameserver 172.22.10.67
search dai.netdai.com netdai.com
/etc/systemd/resolved.conf中dns 172.22.136.2和/etc/netplan/00-installer-config.yaml中dns 172.22.10.66 172.22.10.67，就是沒有來自/etc/resolv.conf的127.0.0.53
root@FRSBachDEV3:~# resolvectl status
Global
Protocols: -LLMNR -mDNS -DNSOverTLS DNSSEC=no/unsupported
resolv.conf mode: stub
Current DNS Server: 172.22.136.2
DNS Servers: 172.22.136.2
Link 2 (ens160)
Current Scopes: DNS
Protocols: +DefaultRoute +LLMNR -mDNS -DNSOverTLS DNSSEC=no/unsupported
Current DNS Server: 172.22.10.66
DNS Servers: 172.22.10.66 172.22.10.67
DNS Domain: dai.netdai.com netdai.com
刪除/etc/resolv.conf來自軟鏈接，并手工建立/etc/resolv.conf文件，其中dns為172.22.136.3
root@FRSBachDEV3:~# ll /etc/resolv.conf
-rw-r--r-- 1 root root 946 Oct 12 10:49 /etc/resolv.conf
root@FRSBachDEV3:~# cat /etc/resolv.conf
nameserver 172.22.136.3
options edns0 trust-ad
search dai.netdai.com netdai.com
保留/etc/systemd/resolved.conf中dns 172.22.136.2的情況下，重啟systemd-resolved，發(fā)現(xiàn)還是用的/etc/systemd/resolved.conf中dns 172.22.136.2而沒有使用手工建立/etc/resolv.conf文件的dns 172.22.136.3
root@FRSBachDEV3:~# systemctl restart systemd-resolved
root@FRSBachDEV3:~# resolvectl status
Global
Protocols: -LLMNR -mDNS -DNSOverTLS DNSSEC=no/unsupported
resolv.conf mode: foreign
DNS Servers: 172.22.136.2
Link 2 (ens160)
Current Scopes: DNS
Protocols: +DefaultRoute +LLMNR -mDNS -DNSOverTLS DNSSEC=no/unsupported
DNS Servers: 172.22.10.66 172.22.10.67
DNS Domain: dai.netdai.com netdai.com
注釋掉/etc/systemd/resolved.conf中dns再重啟systemd-resolved，發(fā)現(xiàn)這個時候才真正用上了手工建立/etc/resolv.conf文件的dns 172.22.136.3
root@FRSBachDEV3:~# vim /etc/systemd/resolved.conf
root@FRSBachDEV3:~# cat /etc/systemd/resolved.conf |grep DNS
#DNS
root@FRSBachDEV3:~# systemctl restart systemd-resolved
root@FRSBachDEV3:~# resolvectl status
Global
Protocols: -LLMNR -mDNS -DNSOverTLS DNSSEC=no/unsupported
resolv.conf mode: foreign
Current DNS Server: 172.22.136.3
DNS Servers: 172.22.136.3
DNS Domain: dai.netdai.com netdai.com
Link 2 (ens160)
Current Scopes: DNS
Protocols: +DefaultRoute +LLMNR -mDNS -DNSOverTLS DNSSEC=no/unsupported
DNS Servers: 172.22.10.66 172.22.10.67
DNS Domain: dai.netdai.com netdai.com
root@FRSBachDEV3:~# cat /run/systemd/resolve/resolv.conf
nameserver 172.22.136.3
nameserver 172.22.10.66
nameserver 172.22.10.67
search dai.netdai.com netdai.com
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