3.5.7 划分子网
划分子网：将一个大的网络（主机数多）划分成多个小的网络（主机数少），主机ID位数变少，网络ID位数变多，网络ID位向主机ID位借位
划分子网的数量由网络ID向主机ID借的位决定
子网数量=2^网络ID向主机ID借位
可变长度子网掩码
Subnet地址
范例：
10.0.0.0/8
2^24-2
172.16.0.0/16
网段数=2^可变的网络ID位
一个网络的最大主机数=2^主机ID的位-2
主机ID位越多,主机数越多,网络越大
主机ID位数变少,主机数量越少,网络越小
划分子网:
10.00 000000.0.0
10.0 0000000.0.1
10.1 1111111.255.254
10.0 0000000.0.0 10.0.0.0/9
10.1 0000000.0.0 10.128.0.0/9
10.00000000.0.0 10.0.0.0/10
10.01000000.0.0 10.64.0.0/10
10.10000000.0.0 10.128.0.0/10
10.11000000.0.0 10.192.0.0/10
划分子网的数量由网络ID向主机ID借的位决定
子网数量=2^网络ID向主机ID借位
范例：
中国移动10.0.0.0/8 给32个各省公司划分对应的子网
1）每个省公司的子网的netmask？
2^5>=32 借5位网络ID
8+5=13
255.11111000.0.0
255.248.0.0
2)每个省公司的子网的主机数有多少？
2^(32-13)-2=524286
3)第一个子网的网络ID?
10.00000 000.0.0
10.0.0.0/13
4）河南省得到第10个子网，网络ID？
10.01001 000.0.0/13
10.72.0.0/13
5）河南省得到第10个子网的最小IP和最大的IP？
10.01001 000.0.1
10.01001 111.11111111.11111110
10.72.0.1---10.79.255.254
6）所有子网中最大，最小的子网的网络ID(NETID)？
10.00000 000.0.0/13 10.0.0.0/13
10.11111 000.0.0/13 10.248.0.0/13
范例：
中国移动10.0.0.0/8 给32个省公司划分对应的子网，河南省得到第10个子网，再给省内的16个地市划分子网
10.01001 000.0.0 10.72.0.0/13
1）每个市公司的子网的netmask？
2^4>=16 借4位网络ID
13+4=17
255.255.128.0
2）每个市公司的子网的主机数有多少？
32-17=15 2^15-2=32766
3）各地市的最小netid和最大netid?
10.72.0.0-10.79.128.0
4）洛阳市第2个子网，最小IP和最大IP？
10.72.128.1-10.72.255.254
10.01001000.00000000.0/17 10.72.0.1-10.72.127.254
10.01001000.10000000.0/17 10.72.128.1-10.72.255.254
10.01001001.00000000.0/17 10.73.0.1-10.73.127.254
10.01001001.10000000.0/17 10.73.128.0-10.73.255.254
10.01001010.00000000.0/17 10.74.0.1-10.74.127.254
10.01001010.10000000.0/17 10.74.128.1-10.74.255.254
10.01001011.00000000.0/17 10.75.0.1-10.75.127.254
10.01001011.10000000.0/17 10.75.128.1-10.75.255.254
10.01001100.00000000.0/17 10.76.0.1-10.76.127.254
10.01001100.10000000.0/17 10.76.128.1-10.76.255.254
10.01001101.00000000.0/17 10.77.0.1-10.77.127.254
10.01001101.10000000.0/17 10.77.128.1-10.77.255.254
10.01001110.00000000.0/17 10.78.0.1-10.78.127.254
10.01001110.10000000.0/17 10.78.128.1-10.255.254
10.01001111.00000000.0/17 10.79.0.1-10.79.127.254
10.01001111.10000000.0/17 10.79.128.1-10.79.255.254
3.5.8 优化IP地址分配
合并超网：将多个小网络合并成一个大网，主机ID位向网络ID位借位，主要实现路由聚合功能
范例：
#2000个主机分配了8个C类网段
220.78.168.0/24
220.78.169.0/24
220.78.170.0/24
220.78.171.0/24
220.78.172.0/24
220.78.173.0/24
220.78.174.0/24
220.78.175.0/24
220.78.10101 000.0 220.78.168.0/24
220.78.10101 001.0 220.78.169.0/24
220.78.10101 010.0 220.78.170.0/24
...
220.78.10101 110.0 220.78.174.0/24
220.78.10101 111.0 220.78.175.0/24
#合并成
220.78.168.0/21
3.5.9 跨网络通信
跨网络通信：路由,选择路径
路由分类：
- 主机路由
- 网络路由
- 默认路由
优先级：精度越高，优先级越高
3.5.10 动态主机配置协议 DHCP
4.网络配置
4.1 基本网络配置
将Linux主机接入到网络，需要配置网络相关设置
一般包括如下内容：
-
主机名
-
IP/netmask
-
路由：默认网关
-
DNS服务器
主DNS服务器
次DNS服务器
第三个DNS服务器
范例：
[root@rocky8 ~]# hostname
rocky8
[root@rocky8 ~]# ping rocky8
PING rocky8(rocky8 (fe80::20c:29ff:fef9:6ad1%eth0)) 56 data bytes
64 bytes from rocky8 (fe80::20c:29ff:fef9:6ad1%eth0): icmp_seq=1 ttl=64 time=0.063 ms
64 bytes from rocky8 (fe80::20c:29ff:fef9:6ad1%eth0): icmp_seq=2 ttl=64 time=0.052 ms
64 bytes from rocky8 (fe80::20c:29ff:fef9:6ad1%eth0): icmp_seq=3 ttl=64 time=0.036 ms
64 bytes from rocky8 (fe80::20c:29ff:fef9:6ad1%eth0): icmp_seq=4 ttl=64 time=0.042 ms
^C
--- rocky8 ping statistics ---
4 packets transmitted, 4 received, 0% packet loss, time 3079ms
rtt min/avg/max/mdev = 0.036/0.048/0.063/0.011 ms
4.2 CentOS 6 之前版本网卡名称
接口命名方式：CentOS 6
以太网：eth[0,1,2,…]
ppp：ppp[0,1,2,…]
网络接口识别并命名相关的udev配置文件：
/etc/udev/rules.d/70-persistent-net.rules
查看网卡：
dmesg |grep –i eth
ethtool -i eth0
卸载网卡驱动：
modprobe -r e1000
rmmod e1000
装载网卡驱动：
modprobe e1000
范例：临时修改网卡名称
[root@centos6 ~]# ip link set eth0 down
[root@centos6 ~]# ip link set eth0 name abc
[root@centos6 ~]# ip link set abc up
范例：
#克隆一台centos6 主机出来
#ethtool -i eth1 查看网卡驱动为e1000
#modprobe -r e1000 卸载网卡驱动
#modprobe e1000 加载网卡驱动
#现在没有IP地址
#ifconfig eth0 172.31.0.66/21，临时修改IP地址
4.3 网络配置命令
4.3.1 网络配置方式
-
静态指定:
ifconfig, route, netstat
ip: object {link, addr, route}, ss, tc
system-config-network-tui，setup
配置文件
-
动态分配：DHCP: Dynamic Host Configuration Protocol
4.3.2 ifconfig命令
来自于net-tools包，建议使用 ip 代替
[root@rocky8 ~]# which ifconfig
/usr/sbin/ifconfig
[root@rocky8 ~]# rpm -qf `which ifconfig`
net-tools-2.0-0.52.20160912git.el8.x86_64
[root@rocky8 ~]# rpm -qi net-tools
Name : net-tools
Version : 2.0
Release : 0.52.20160912git.el8
Architecture: x86_64
Install Date: Mon 25 Oct 2021 05:22:25 PM CST
Group : System Environment/Base
Size : 964894
License : GPLv2+
Signature : RSA/SHA256, Mon 12 Apr 2021 06:31:49 AM CST, Key ID 15af5dac6d745a60
Source RPM : net-tools-2.0-0.52.20160912git.el8.src.rpm
Build Date : Wed 07 Apr 2021 11:41:10 AM CST
Build Host : ord1-prod-x86build001.svc.aws.rockylinux.org
Relocations : (not relocatable)
Packager : infrastructure@rockylinux.org
Vendor : Rocky
URL : http://sourceforge.net/projects/net-tools/
Summary : Basic networking tools
Description :
The net-tools package contains basic networking tools,
including ifconfig, netstat, route, and others.
Most of them are obsolete. For replacement check iproute package.
[root@rocky8 ~]# rpm -ql net-tools
/usr/bin/netstat
/usr/lib/.build-id
/usr/lib/.build-id/02
/usr/lib/.build-id/02/9bd2bbada4d981bd08eec1b69c417ec0540464
/usr/lib/.build-id/18
/usr/lib/.build-id/18/e13de699b88ffca36b146a8173afd31ffa4bfa
/usr/lib/.build-id/38
/usr/lib/.build-id/38/d5f513a2c3495d28e4aa0618ced7aa8b091719
/usr/lib/.build-id/3f
/usr/lib/.build-id/3f/7dd7b481bc94f655e33d5c48f82850cde2c2dd
/usr/lib/.build-id/40
/usr/lib/.build-id/40/7e45207270c9a482333d312954a9b57b1a4ef0
/usr/lib/.build-id/4b
/usr/lib/.build-id/4b/eae4ed5cd7e395e1affac0bb264b8060cc3855
/usr/lib/.build-id/88
/usr/lib/.build-id/88/26fdea3b3a6b0fb11618354fe056ee1170c2a1
/usr/lib/.build-id/93
/usr/lib/.build-id/93/66d7a14b144fd1470e4ded9971f70fb81feeba
/usr/lib/.build-id/98
/usr/lib/.build-id/98/655a9c5c9a4728d1c25101a56f3149fa10b329
/usr/lib/.build-id/a5
/usr/lib/.build-id/a5/ef7e9bb55436dc8eb3d2414afd40c1df134640
/usr/lib/.build-id/af
/usr/lib/.build-id/af/dcfd9fa89871631d511adc2fc5affac225d8eb
/usr/lib/.build-id/e4
/usr/lib/.build-id/e4/5566d09948e5656abffefaf0aa81521012e80f
/usr/lib/systemd/system/arp-ethers.service
/usr/sbin/arp
/usr/sbin/ether-wake
/usr/sbin/ifconfig
/usr/sbin/ipmaddr
/usr/sbin/iptunnel
/usr/sbin/mii-diag
/usr/sbin/mii-tool
/usr/sbin/nameif
/usr/sbin/plipconfig
/usr/sbin/route
/usr/sbin/slattach
/usr/share/licenses/net-tools
/usr/share/licenses/net-tools/COPYING
/usr/share/locale/cs/LC_MESSAGES/net-tools.mo
/usr/share/locale/de/LC_MESSAGES/net-tools.mo
/usr/share/locale/et_EE/LC_MESSAGES/net-tools.mo
/usr/share/locale/fr/LC_MESSAGES/net-tools.mo
/usr/share/locale/pt_BR/LC_MESSAGES/net-tools.mo
/usr/share/man/de/man5/ethers.5.gz
/usr/share/man/de/man8/arp.8.gz
/usr/share/man/de/man8/ifconfig.8.gz
/usr/share/man/de/man8/netstat.8.gz
/usr/share/man/de/man8/plipconfig.8.gz
/usr/share/man/de/man8/route.8.gz
/usr/share/man/de/man8/slattach.8.gz
/usr/share/man/fr/man5/ethers.5.gz
/usr/share/man/fr/man8/arp.8.gz
/usr/share/man/fr/man8/ifconfig.8.gz
/usr/share/man/fr/man8/netstat.8.gz
/usr/share/man/fr/man8/plipconfig.8.gz
/usr/share/man/fr/man8/route.8.gz
/usr/share/man/fr/man8/slattach.8.gz
/usr/share/man/man5/ethers.5.gz
/usr/share/man/man8/arp.8.gz
/usr/share/man/man8/ether-wake.8.gz
/usr/share/man/man8/ifconfig.8.gz
/usr/share/man/man8/ipmaddr.8.gz
/usr/share/man/man8/iptunnel.8.gz
/usr/share/man/man8/mii-diag.8.gz
/usr/share/man/man8/mii-tool.8.gz
/usr/share/man/man8/nameif.8.gz
/usr/share/man/man8/netstat.8.gz
/usr/share/man/man8/plipconfig.8.gz
/usr/share/man/man8/route.8.gz
/usr/share/man/man8/slattach.8.gz
/usr/share/man/pt/man8/arp.8.gz
/usr/share/man/pt/man8/ifconfig.8.gz
/usr/share/man/pt/man8/netstat.8.gz
/usr/share/man/pt/man8/route.8.gz
[root@rocky8 ~]# ifconfig
eth0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500
inet 172.31.1.8 netmask 255.255.248.0 broadcast 172.31.7.255
inet6 fe80::20c:29ff:fef9:6ad1 prefixlen 64 scopeid 0x20<link>
ether 00:0c:29:f9:6a:d1 txqueuelen 1000 (Ethernet)
RX packets 22894 bytes 32929773 (31.4 MiB)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 2364 bytes 214404 (209.3 KiB)
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 8 bytes 832 (832.0 B)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 8 bytes 832 (832.0 B)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
ifconfig [interface]
ifconfig -a
ifconfig IFACE [up|down]
ifconfig interface [aftype] options | address ...
ifconfig IFACE IP/netmask [up]
ifconfig IFACE IP netmask NETMASK
注意：立即生效
启用混杂模式：[-]promisc
范例：
#添加一块网卡
[root@centos6 ~]# ifconfig
eth0 Link encap:Ethernet HWaddr 00:0C:29:18:63:F7
inet addr:172.31.0.66 Bcast:172.31.7.255 Mask:255.255.248.0
inet6 addr: fe80::20c:29ff:fe18:63f7/64 Scope:Link
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:87 errors:0 dropped:0 overruns:0 frame:0
TX packets:67 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:12998 (12.6 KiB) TX bytes:11638 (11.3 KiB)
lo Link encap:Local Loopback
inet addr:127.0.0.1 Mask:255.0.0.0
inet6 addr: ::1/128 Scope:Host
UP LOOPBACK RUNNING MTU:65536 Metric:1
RX packets:0 errors:0 dropped:0 overruns:0 frame:0
TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:0
RX bytes:0 (0.0 b) TX bytes:0 (0.0 b)
#默认是看不到的
[root@centos6 ~]# ifconfig -a #可以看到被禁用的网卡
eth0 Link encap:Ethernet HWaddr 00:0C:29:18:63:F7
inet addr:172.31.0.66 Bcast:172.31.7.255 Mask:255.255.248.0
inet6 addr: fe80::20c:29ff:fe18:63f7/64 Scope:Link
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:97 errors:0 dropped:0 overruns:0 frame:0
TX packets:73 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:13888 (13.5 KiB) TX bytes:13274 (12.9 KiB)
eth1 Link encap:Ethernet HWaddr 00:0C:29:18:63:01
BROADCAST MULTICAST MTU:1500 Metric:1
RX packets:0 errors:0 dropped:0 overruns:0 frame:0
TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:0 (0.0 b) TX bytes:0 (0.0 b)
lo Link encap:Local Loopback
inet addr:127.0.0.1 Mask:255.0.0.0
inet6 addr: ::1/128 Scope:Host
UP LOOPBACK RUNNING MTU:65536 Metric:1
RX packets:0 errors:0 dropped:0 overruns:0 frame:0
TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:0
RX bytes:0 (0.0 b) TX bytes:0 (0.0 b)
[root@centos6 ~]# ifconfig eth1 up #启用网卡
[root@centos6 ~]# ifconfig
eth0 Link encap:Ethernet HWaddr 00:0C:29:18:63:F7
inet addr:172.31.0.66 Bcast:172.31.7.255 Mask:255.255.248.0
inet6 addr: fe80::20c:29ff:fe18:63f7/64 Scope:Link
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:125 errors:0 dropped:0 overruns:0 frame:0
TX packets:93 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:16390 (16.0 KiB) TX bytes:16556 (16.1 KiB)
eth1 Link encap:Ethernet HWaddr 00:0C:29:18:63:01
inet6 addr: fe80::20c:29ff:fe18:6301/64 Scope:Link
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:0 errors:0 dropped:0 overruns:0 frame:0
TX packets:3 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:0 (0.0 b) TX bytes:238 (238.0 b)
lo Link encap:Local Loopback
inet addr:127.0.0.1 Mask:255.0.0.0
inet6 addr: ::1/128 Scope:Host
UP LOOPBACK RUNNING MTU:65536 Metric:1
RX packets:0 errors:0 dropped:0 overruns:0 frame:0
TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:0
RX bytes:0 (0.0 b) TX bytes:0 (0.0 b)
[root@centos6 ~]# ifconfig eth0:1 172.31.0.76/21 #设置网卡别名IP地址
[root@centos6 ~]# ifconfig
eth0 Link encap:Ethernet HWaddr 00:0C:29:18:63:F7
inet addr:172.31.0.66 Bcast:172.31.7.255 Mask:255.255.248.0
inet6 addr: fe80::20c:29ff:fe18:63f7/64 Scope:Link
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:201 errors:0 dropped:0 overruns:0 frame:0
TX packets:144 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:23544 (22.9 KiB) TX bytes:23762 (23.2 KiB)
eth0:1 Link encap:Ethernet HWaddr 00:0C:29:18:63:F7
inet addr:172.31.0.76 Bcast:172.31.7.255 Mask:255.255.248.0
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
eth1 Link encap:Ethernet HWaddr 00:0C:29:18:63:01
inet6 addr: fe80::20c:29ff:fe18:6301/64 Scope:Link
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:0 errors:0 dropped:0 overruns:0 frame:0
TX packets:6 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:0 (0.0 b) TX bytes:468 (468.0 b)
lo Link encap:Local Loopback
inet addr:127.0.0.1 Mask:255.0.0.0
inet6 addr: ::1/128 Scope:Host
UP LOOPBACK RUNNING MTU:65536 Metric:1
RX packets:0 errors:0 dropped:0 overruns:0 frame:0
TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:0
RX bytes:0 (0.0 b) TX bytes:0 (0.0 b)
[root@centos6 ~]# ifconfig eth0:1 down #禁用网卡别名
[root@centos6 ~]# ifconfig eth1 172.31.0.86/21
[root@centos6 ~]# ifconfig
eth0 Link encap:Ethernet HWaddr 00:0C:29:18:63:F7
inet addr:172.31.0.66 Bcast:172.31.7.255 Mask:255.255.248.0
inet6 addr: fe80::20c:29ff:fe18:63f7/64 Scope:Link
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:273 errors:0 dropped:0 overruns:0 frame:0
TX packets:191 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:30284 (29.5 KiB) TX bytes:30720 (30.0 KiB)
eth1 Link encap:Ethernet HWaddr 00:0C:29:18:63:01
inet addr:172.31.0.86 Bcast:172.31.7.255 Mask:255.255.248.0
inet6 addr: fe80::20c:29ff:fe18:6301/64 Scope:Link
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:0 errors:0 dropped:0 overruns:0 frame:0
TX packets:6 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:0 (0.0 b) TX bytes:468 (468.0 b)
lo Link encap:Local Loopback
inet addr:127.0.0.1 Mask:255.0.0.0
inet6 addr: ::1/128 Scope:Host
UP LOOPBACK RUNNING MTU:65536 Metric:1
RX packets:0 errors:0 dropped:0 overruns:0 frame:0
TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:0
RX bytes:0 (0.0 b) TX bytes:0 (0.0 b)
[root@centos6 ~]# ifdown eth1
usage: ifdown <device name>
#禁用不了，因为eth1没有网卡配置文件
#ifdown eth1只是删除了IP地址，ifconfig eth1 down 是禁用了网卡
[root@centos6 ~]# ifconfig eth1 0/0 这样也可以清除IP地址
SIOCSIFNETMASK: Cannot assign requested address
SIOCGIFADDR: Cannot assign requested address
SIOCSIFBROADCAST: Cannot assign requested address
[root@centos6 ~]# ifconfig -s
Iface MTU Met RX-OK RX-ERR RX-DRP RX-OVR TX-OK TX-ERR TX-DRP TX-OVR Flg
eth0 1500 0 387 0 0 0 273 0 0 0 BMRU
eth1 1500 0 0 0 0 0 6 0 0 0 BMRU
lo 65536 0 0 0 0 0 0 0 0 0 LRU
#-s 统计网卡流量
[root@rocky8 ~]# watch -n0.5 ifconfig -s
Every 0.5s: ifconfig -s rocky8: Mon Oct 25 18:25:14 2021
Iface MTU RX-OK RX-ERR RX-DRP RX-OVR TX-OK TX-ERR TX-DRP TX-OVR Flg
eth0 1500 22994 0 0 0 2452 0 0 0 BMRU
eth1 1500 7 0 0 0 16 0 0 0 BMRU
lo 65536 8 0 0 0 8 0 0 0 LRU
[root@centos7 ~]# ping -f 172.31.1.8 #-f flood 泛洪
PING 172.31.1.8 (172.31.1.8) 56(84) bytes of data.
[root@centos7 ~]# ping -s 65508 -f 172.31.1.8
Error: packet size 65508 is too large. Maximum is 65507
#-s 指定一次多少字节 ，最大65507字节
[root@centos7 ~]# ping -s 65507 -f 172.31.1.8
PING 172.31.1.8 (172.31.1.8) 65507(65535) bytes of data.
范例:
[root@rocky8 ~]# ifconfig eth0 10.0.0.68 netmask 255.255.0.0
#清除eth0上面的IP地址
[root@rocky8 ~]# ifconfig eth0 0.0.0.0/0
#启用和禁用网卡
[root@rocky8 ~]# ifconfig eth0 down
[root@rocky8 ~]# ifconfig eth0 up
#对一个网卡设置多个IP地址
[root@rocky8 ~]# ifconfig eth0:1 172.16.0.8/24
[root@rocky8 ~]# ifconfig
eth0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500
inet 172.31.1.8 netmask 255.255.248.0 broadcast 172.31.7.255
inet6 fe80::20c:29ff:fef9:6ad1 prefixlen 64 scopeid 0x20<link>
ether 00:0c:29:f9:6a:d1 txqueuelen 1000 (Ethernet)
RX packets 22234 bytes 32826530 (31.3 MiB)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 1892 bytes 160671 (156.9 KiB)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
eth0:1: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500
inet 172.16.0.8 netmask 255.255.255.0 broadcast 172.16.0.255
ether 00:0c:29:f9:6a:d1 txqueuelen 1000 (Ethernet)
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 0 bytes 0 (0.0 B)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 0 bytes 0 (0.0 B)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
[root@rocky8 ~]# ifconfig eth0:1 down
[root@rocky8 ~]# ifconfig
eth0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500
inet 172.31.1.8 netmask 255.255.248.0 broadcast 172.31.7.255
inet6 fe80::20c:29ff:fef9:6ad1 prefixlen 64 scopeid 0x20<link>
ether 00:0c:29:f9:6a:d1 txqueuelen 1000 (Ethernet)
RX packets 22244 bytes 32827424 (31.3 MiB)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 1900 bytes 162751 (158.9 KiB)
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 0 bytes 0 (0.0 B)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 0 bytes 0 (0.0 B)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
范例:
[root@rocky8 ~]# ifconfig -s
Iface MTU RX-OK RX-ERR RX-DRP RX-OVR TX-OK TX-ERR TX-DRP TX-OVR Flg
eth0 1500 22251 0 0 0 1908 0 0 0 BMRU
lo 65536 0 0 0 0 0 0 0 0 LRU
[root@rocky8 ~]# ifconfig -s eth0
Iface MTU RX-OK RX-ERR RX-DRP RX-OVR TX-OK TX-ERR TX-DRP TX-OVR Flg
eth0 1500 22265 0 0 0 1917 0 0 0 BMRU