1.网卡命名
1.1 传统网卡命名机制
传统命名:
以太网eth[0,1,2,...]
wlan[0,1,2,...]
1.2 redhat7网卡命名机制
systemd对网络设备的命名方式:
如果Firmware或BIOS为主板上集成的设备提供的索引信息可用,且可预测,则根据此索引进行命名,例如eno1
如果Firmware或BIOS为PCI-E扩展槽所提供的索引信息可用,且可预测,则根据此索引进行命名,例如ens1
如果硬件接口的物理位置信息可用,则根据此信息进行命名,例如enp2s0
如果用户显式启动,也可根据MAC地址进行命名,例如enx2387a1dc56
上述均不可用时,则使用传统命名机制
上述命名机制中,有的需要biosdevname程序的参与。所以必须安装biosdevname程序且启用它。
1.3 网络接口名称组成格式
基于固件、设备结构、设备类型
由两个字母开头标示固件
以太网网卡以 en 开头
无线网卡以 wl 开头
设备结构
o:主板上集成的设备的设备索引号
s
x:基于MAC地址的命名
p
1.4 网卡设备的命名过程
udev,辅助工具程序/lib/udev/rename_device会根据/usr/lib/udev/rules.d/60-net.rules中的信息设定网卡名称
biosdevname会根据/usr/lib/udev/rules.d/71-biosdevname.rules中的信息设定网卡名称
通过udev检测网络接口设备,根据/usr/lib/udev/rules.d/75-net-description中的变量信息设定网卡名称
1.5 回归传统命名
//修改网卡配置文件 [root@localhost ~]# cd /etc/sysconfig/network-scripts/ [root@localhost network-scripts]# mv ifcfg-ens33 ifcfg-eth0 [root@localhost network-scripts]# vim ifcfg-eth0 TYPE=Ethernet BOOTPROTO=dhcp DEFROUTE=yes IPV4_FAILURE_FATAL=no NAME=eth0 //此处要把ens33改成eht0 UUID=03be31f5-a3c1-4f8d-88b3-aea6e85c869f DEVICE=eth0 //此处要把ens33改成eht0 ONBOOT=yes //编辑/etc/default/grub配置文件,在以GRUB_CMDLINE_LINUX开头的行内rhgb的前面加上net.ifnames=0 biosdevname=0 [root@localhost ~]# vim /etc/default/grub GRUB_TIMEOUT=5 GRUB_DISTRIBUTOR="$(sed 's, release .*$,,g' /etc/system-release)" GRUB_DEFAULT=saved GRUB_DISABLE_SUBMENU=true GRUB_TERMINAL_OUTPUT="console" GRUB_CMDLINE_LINUX="crashkernel=auto rd.lvm.lv=rhel/root rd.lvm.lv=rhel/swap net.ifnames=0 biosdevname=0 rhgb quiet" GRUB_DISABLE_RECOVERY="true" //为grub2生成其配置文件 [root@localhost ~]# grub2-mkconfig -o /etc/grub2.cfg Generating grub configuration file ... Found linux image: /boot/vmlinuz-3.10.0-693.el7.x86_64 Found initrd image: /boot/initramfs-3.10.0-693.el7.x86_64.img Found linux image: /boot/vmlinuz-0-rescue-fd0bcf5782d24ba5b903b175c35f328e Found initrd image: /boot/initramfs-0-rescue-fd0bcf5782d24ba5b903b175c35f328e.img done //重启系统 [root@localhost ~]# reboot
2. 网络管理常用命令
2.1 ifconfig
//查看当前处于活动状态的所有网络接口 [root@localhost ~]# ifconfig eth0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500 inet 192.168.124.134 netmask 255.255.255.0 broadcast 192.168.124.255 inet6 fe80::14bd:bb10:c3ee:f87 prefixlen 64 scopeid 0x20<link> ether 00:0c:29:76:10:14 txqueuelen 1000 (Ethernet) RX packets 884 bytes 75762 (73.9 KiB) RX errors 0 dropped 0 overruns 0 frame 0 TX packets 944 bytes 74081 (72.3 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 1 (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 //仅查看eth0网卡状态 [root@localhost ~]# ifconfig eth0 eth0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500 inet 192.168.124.134 netmask 255.255.255.0 broadcast 192.168.124.255 inet6 fe80::14bd:bb10:c3ee:f87 prefixlen 64 scopeid 0x20<link> ether 00:0c:29:76:10:14 txqueuelen 1000 (Ethernet) RX packets 898 bytes 76820 (75.0 KiB) RX errors 0 dropped 0 overruns 0 frame 0 TX packets 954 bytes 75827 (74.0 KiB) TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0 //查看所有网卡状态信息, 包括禁用和启用 [root@localhost ~]# ifconfig -a eth0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500 inet 192.168.124.134 netmask 255.255.255.0 broadcast 192.168.124.255 inet6 fe80::14bd:bb10:c3ee:f87 prefixlen 64 scopeid 0x20<link> ether 00:0c:29:76:10:14 txqueuelen 1000 (Ethernet) RX packets 918 bytes 78328 (76.4 KiB) RX errors 0 dropped 0 overruns 0 frame 0 TX packets 967 bytes 77523 (75.7 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 1 (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 //网卡配置信息含义如下: UP: 网卡处于活动状态 BROADCAST: 支持广播 RUNNING: 网线已接入 MULTICAST: 支持组播 MTU: 最大传输单元(字节),即此接口一次所能传输的最大封包 inet: 显示IPv4地址行 inet6: 显示IPv6地址行 link/enther: 指设备硬件(MAC)地址 txqueuelen: 传输缓存区长度大小 RX packets: 接收的数据包 TX packets: 发送的数据包 errors: 总的收包的错误数量 dropped: 由于各种原因, 导致拷贝在内存过程中被丢弃 collisions: 网络信号冲突情况, 值不为0则可能存在网络故障
2.2 ip
//语法:ip [ OPTIONS ] OBJECT { COMMAND | help } OBJECT: link:网络接口属性 addr:协议地址 route:路由 //查看网络接口所有地址 [root@localhost ~]# ip link show 1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN mode DEFAULT qlen 1 link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00 2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP mode DEFAULT qlen 1000 link/ether 00:0c:29:76:10:14 brd ff:ff:ff:ff:ff:ff //显示报文统计信息 [root@localhost ~]# ip -s link show 1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN mode DEFAULT qlen 1 link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00 RX: bytes packets errors dropped overrun mcast 0 0 0 0 0 0 TX: bytes packets errors dropped carrier collsns 0 0 0 0 0 0 2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP mode DEFAULT qlen 1000 link/ether 00:0c:29:76:10:14 brd ff:ff:ff:ff:ff:ff RX: bytes packets errors dropped overrun mcast 84542 997 0 0 0 0 TX: bytes packets errors dropped carrier collsns 83317 1019 0 0 0 0 //启用或禁用网络接口ip link set DEV {up|down} [root@localhost ~]# ip link set lo down [root@localhost ~]# ip link show 1: lo: <LOOPBACK> mtu 65536 qdisc noqueue state DOWN mode DEFAULT qlen 1 link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00 2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP mode DEFAULT qlen 1000 link/ether 00:0c:29:76:10:14 brd ff:ff:ff:ff:ff:ff [root@localhost ~]# ip link set lo up [root@localhost ~]# ip link show 1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN mode DEFAULT qlen 1 link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00 2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP mode DEFAULT qlen 1000 link/ether 00:0c:29:76:10:14 brd ff:ff:ff:ff:ff:ff //ip addr add ADDRESS dev DEV:添加IP地址 [root@localhost ~]# ip addr show eth0 2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000 link/ether 00:0c:29:76:10:14 brd ff:ff:ff:ff:ff:ff inet 192.168.124.134/24 brd 192.168.124.255 scope global dynamic eth0 valid_lft 1421sec preferred_lft 1421sec inet6 fe80::14bd:bb10:c3ee:f87/64 scope link valid_lft forever preferred_lft forever [root@localhost ~]# ip addr add 192.168.1.1/24 dev eth0 [root@localhost ~]# ip addr show eth0 2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000 link/ether 00:0c:29:76:10:14 brd ff:ff:ff:ff:ff:ff inet 192.168.124.134/24 brd 192.168.124.255 scope global dynamic eth0 valid_lft 1320sec preferred_lft 1320sec inet 192.168.1.1/24 scope global eth0 valid_lft forever preferred_lft forever inet6 fe80::14bd:bb10:c3ee:f87/64 scope link valid_lft forever preferred_lft forever //ip addr del ADDRESS dev DEV:删除IP地址 [root@localhost ~]# ip addr show eth0 2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000 link/ether 00:0c:29:76:10:14 brd ff:ff:ff:ff:ff:ff inet 192.168.124.134/24 brd 192.168.124.255 scope global dynamic eth0 valid_lft 1704sec preferred_lft 1704sec inet 192.168.1.1/24 scope global eth0 valid_lft forever preferred_lft forever inet6 fe80::14bd:bb10:c3ee:f87/64 scope link valid_lft forever preferred_lft forever [root@localhost ~]# ip addr del 192.168.1.1/24 dev eth0 [root@localhost ~]# ip addr show eth0 2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000 link/ether 00:0c:29:76:10:14 brd ff:ff:ff:ff:ff:ff inet 192.168.124.134/24 brd 192.168.124.255 scope global dynamic eth0 valid_lft 1664sec preferred_lft 1664sec inet6 fe80::14bd:bb10:c3ee:f87/64 scope link valid_lft forever preferred_lft forever //ip addr show DEV:查看网络接口的地址 [root@localhost ~]# ip addr show eth0 2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000 link/ether 00:0c:29:76:10:14 brd ff:ff:ff:ff:ff:ff inet 192.168.124.134/24 brd 192.168.124.255 scope global dynamic eth0 valid_lft 1575sec preferred_lft 1575sec inet6 fe80::14bd:bb10:c3ee:f87/64 scope link valid_lft forever preferred_lft forever //ip route:routing table management 路由管理 //添加路由:ip route add TARGET via GW dev IFACE src SOURCE_IP TARGET: 主机路由:IP 网络路由:NETWORK/MASK //删除路由:ip route del TARGET TARGET: 主机路由:IP 网络路由:NETWORK/MASK //查看路由:ip route show //刷新路由表:ip route flush [dev IFACE] [via PREFIX]
2.3 route
Linux主机之间是使用IP进行通信, 假设A主机和B主机同在一个网段内且网卡都处于激活状态, 则A具备和B直接通信的能力, 但如果A主机和B主机处于两个不同的网段, 则A必须通过路由器才能和B通信, 路由器属于IT设备的基础设施, 每一个网段都应该至少有一个网关
//查看当前路由表 [root@localhost ~]# route Kernel IP routing table Destination Gateway Genmask Flags Metric Ref Use Iface default gateway 0.0.0.0 UG 100 0 0 eth0 192.168.124.0 0.0.0.0 255.255.255.0 U 100 0 0 eth0 //以数字方式显示各主机或端口等相关信息 [root@localhost ~]# route -n Kernel IP routing table Destination Gateway Genmask Flags Metric Ref Use Iface 0.0.0.0 192.168.124.2 0.0.0.0 UG 100 0 0 eth0 192.168.124.0 0.0.0.0 255.255.255.0 U 100 0 0 eth0 //增加路由 //语法:route add [-net|-host] target [netmask Nm] [gw Gw] [[dev] If] //增加网段路由 [root@localhost ~]# route add -net 172.16.12.0/24 gw 172.16.12.2 dev eth1 [root@localhost ~]# route add -net 0.0.0.0/0 gw 172.16.12.2 dev eth1 //增加主机路由 [root@localhost ~]# route add -host 172.16.12.128 gw 172.16.12.2 //删除路由 [root@localhost ~]# route del -net 172.16.12.0/24 [root@localhost ~]# route del -net 0.0.0.0/0 gw 172.16.12.2
2.4 hostname与hostnamectl
生产环境中必须配置主机名,同时主机名也需要遵循一定的规范, 比如:
公有云: 地区-项目-业务-服务-节点-地址 wh-shop-register-nginx-node1-192.168.56.13 wh-med-pay-mysql-master01-192.168.56.11 wh-med-pay-mysql-slave01-192.168.56.12 //hostname查看主机名 [root@localhost ~]# hostname localhost.localdomain //rhel7系统建议使用hostnamectl修改和查看主机名 //设定永久名称 [root@localhost ~]# cat /etc/hostname localhost.localdomain [root@localhost ~]# hostnamectl set-hostname liping [root@localhost ~]# cat /etc/hostname liping //查看主机信息 [root@localhost ~]# hostnamectl Static hostname: liping Icon name: computer-vm Chassis: vm Machine ID: 6853500258764b1fae8e52afc08a5ff9 Boot ID: 226fa1dc43b1410fb55601c65bc6af81 Virtualization: vmware Operating System: Red Hat Enterprise Linux Server 7.4 (Maipo) CPE OS Name: cpe:/o:redhat:enterprise_linux:7.4:GA:server Kernel: Linux 3.10.0-693.el7.x86_64 Architecture: x86-64
3. 网络相关配置文件
注意:在Linux中以命令方式修改网络配置只在当前状态有效,重启后将失效。故若想使修改的配置重启后依然有效,则必须编辑配置文件进行配置的修改。
3.1 网络配置文件
//网络配置文件:/etc/sysconfig/network NETWORKING={yes|no}:设定整个系统是否启用网络功能,若设为no,则不论网卡如何设置都不能使用网络功能。 HOSTNAME:设置主机名
3.2 网络接口配置文件
网络接口即网卡,其配置文件的路径是/etc/sysconfig/network-scripts/ifcfg-INTERFACE_NAME
[root@localhost ~]# vi /etc/sysconfig/network-scripts/ifcfg-eth1 TYPE=Ethernet BOOTPROTO=static NAME=eth1 UUID=03be31f5-a3c1-4f8d-88b3-aea6e85c869f DEVICE=eth1 ONBOOT=yes IPADDR=172.16.12.130 NETMASK=255.255.255.0 GATEWAY=172.16.12.2 DNS1=172.16.12.2 //网卡配置说明 //参数 说明 BOOTPROTO=none //引导协议,可选值有{static|none|dhcp|bootp}。如果要使用静态地址,使用static或none都可以 NM_CONTROLLED //NM是NetworkManager的简写,NM是由RHEL研发的在RHEL6中取代network脚本来实现网络管理、配置的服务脚本 //可选值有{ yes | no } //此项是设定此网卡是否接受NM控制。CentOS6建议设为“no” TYPE //接口类型。常见的接口类型有:Ethernet,Bridge UUID //设备的惟一标识 HWADDR //硬件地址,要与硬件中的地址保持一致,可省 IPADDR=172.16.12.130 //固定IP地址 PREFIX=24 //子网掩码 NETMASK=255.255.255.0 //子网掩码 GATEWAY=172.16.12.2 //默认网关 DNS1=172.16.12.2 //第一个DNS服务器指向 DNS2 //第二个DNS服务器指向 DNS3 //第三个DNS服务器指向 DEVICE=eth1 //关联的设备名称,要与文件名的后半部"INTERFACE_NAME"保持一致 NAME="eth1" //连接名称 ONBOOT=yes //在系统引导时是否自动激活此网络接口,可选值有{ yes | no } DEFROUTE=yes //将接口设定为默认路由[yes|no] USERCTL={yes|no} //是否允许普通用户控制此接口的启用与禁用 PEERDNS={yes|no} //是否在BOOTPROTO为dhcp时接受由dhcp服务器指定的DNS地址,此项设为yes时获得的DNS地址将直接覆盖至/etc/resolv.conf文件中
3.3 路由配置文件
路由配置文件的路径是/etc/sysconfig/network-scripts/route-INTERFACE_NAME
//添加格式一:DEST via NEXTHOP [root@localhost ~]# vi /etc/sysconfig/network-scripts/route-ens33 172.16.12.0/24 via 172.16.12.2 //添加格式二: [root@localhost ~]# vi /etc/sysconfig/network-scripts/route-ens33 ADDRESS0=172.16.12.0 NETMASK0=255.255.255.0 GATEWAY0=172.16.12.2
3.4 DNS配置文件
DNS配置文件的路径是/etc/resolv.conf
[root@localhost ~]# vi /etc/resolv.conf # Generated by NetworkManager search localdomain nameserver 192.168.124.2
4. NetworkManager管理网络
RHEL/CentOS7系统默认使用NetworkManager来提供网络服务,这是一种动态管理网络配置的守护进程,能够让网络设备保持连接状态。
NetworkManager提供的命令行和图形配置工具对网络进行设定, 设定保存的配置文件在/etc/sysconfig/network-scripts目录下, 工具有 nmcli, nmtui, nm-connect-editor
device物理设备, 例如 ens33,enp2s0,virbr0,team0
connection连接设置, 具体网络配置方案
1.不同的网络连接配置可以应用到相同的物理设备,但物理设备同一时间只能应用其中某个网络连接
2.针对物理网络接口, 设定不同的网络连接, 在不同的使用环境中激活相应的网络连接,就可以实现网络配置信息的自动切换了
使用nmcli命令查看设备以及连接情况
//查看设备状态 [root@localhost ~]# nmcli device 设备 类型 状态 连接 eth0 ethernet 连接的 eth0 lo loopback 未托管 -- //查看指定设备的详细状态 [root@localhost ~]# nmcli device show eth0 GENERAL.设备: eth0 GENERAL.类型: ethernet GENERAL.硬盘: 00:0C:29:76:10:14 GENERAL.MTU: 1500 GENERAL.状态: 100 (连接的) GENERAL.连接: eth0 GENERAL.连接路径: /org/freedesktop/NetworkManager/ActiveConnection/1 WIRED-PROPERTIES.载波: 开 IP4.地址[1]: 192.168.124.134/24 IP4.网关: 192.168.124.2 IP4.DNS[1]: 192.168.124.2 IP4.域[1]: localdomain IP6.地址[1]: fe80::14bd:bb10:c3ee:f87/64 IP6.网关: -- //查看连接状态 [root@localhost ~]# nmcli connection 名称 UUID 类型 设备 eth0 8f352a0a-d25c-465c-9488-15a067f71d37 802-3-ethernet eth0 //查看指定设备连接的详细情况 [root@localhost ~]# nmcli connection show eth0 connection.id: eth0 connection.uuid: 8f352a0a-d25c-465c-9488-15a067f71d37 connection.stable-id: -- connection.interface-name: eth0 connection.type: 802-3-ethernet connection.autoconnect: yes connection.autoconnect-priority: 0 connection.autoconnect-retries: -1 (默认) connection.timestamp: 1570517882 connection.read-only: no connection.permissions: -- connection.zone: -- connection.master: -- connection.slave-type: -- connection.autoconnect-slaves: -1 (默认) connection.secondaries: -- connection.gateway-ping-timeout: 0 connection.metered: 未知 connection.lldp: -1 (default) ...
5. 使用原生network管理网络
CentOS/RHEL的网络配置文件默认目录为/etc/sysconfig/network-scripts
默认第一块物理网卡配置文件为ifcfg-eth0, 如果有第二块物理网卡, 配置文件则为ifcfg-eth1以此类推。 注意: 如果新增物理网卡没有配置文件,可选择复制系统默认的进行修改。
//设置NetworkManger开机不启动, 同时停止NetworkManger服务 [root@localhost ~]# systemctl disable NetworkManager [root@localhost ~]# systemctl stop NetworkManager //添加一块物理网卡, 然后新增网络连接配置文件 //复制配置eth0配置文件为eth1 [root@localhost ~]# cp /etc/sysconfig/network-scripts/{ifcfg-eth0,ifcfg-eth1} //编辑网卡配置文件 [root@localhost ~]# vi /etc/sysconfig/network-scripts/ifcfg-eth1 TYPE=Ethernet BOOTPROTO=static NAME=eth1 UUID=03be31f5-a3c1-4f8d-88b3-aea6e85c869f DEVICE=eth1 NM_CONTROLLED=no ONBOOT=yes IPADDR=172.16.12.130 NETMASK=255.255.255.0 GATEWAY=172.16.12.2 DNS1=172.16.12.2 //重启network网络服务加载网络并设置开机启动 [root@localhost ~]# systemctl restart network [root@localhost ~]# systemctl enable network
6. 网络检测工具与故障排查
6.1 ping
ping命令的目的在于测试另一台主机是否可达, 如果ping不到某台主机,就说明对方主机已经出现了问题, 但是不排除由于链路中的防火墙、ping被丢弃等原因造成ping不通的情况
//ping命令常用选项: -c 指定ping的次数 -i 指定ping包的发送间隔 -w 如果ping没有回应, 则在指定超时时间后退出 [root@localhost ~]# ping -c 4 -i 2 www.baidu.com PING www.a.shifen.com (182.61.200.7) 56(84) bytes of data. 64 bytes from 182.61.200.7 (182.61.200.7): icmp_seq=1 ttl=128 time=28.2 ms 64 bytes from 182.61.200.7 (182.61.200.7): icmp_seq=2 ttl=128 time=32.4 ms 64 bytes from 182.61.200.7 (182.61.200.7): icmp_seq=3 ttl=128 time=29.5 ms 64 bytes from 182.61.200.7 (182.61.200.7): icmp_seq=4 ttl=128 time=30.5 ms --- www.a.shifen.com ping statistics --- 4 packets transmitted, 4 received, 0% packet loss, time 6014ms rtt min/avg/max/mdev = 28.207/30.166/32.410/1.537 ms
6.2 host与nslookup
host/nslookup命令用于查询DNS记录
[root@localhost ~]# host www.baidu.com www.baidu.com is an alias for www.a.shifen.com. www.a.shifen.com has address 119.75.216.20 www.a.shifen.com has address 119.75.213.61 [root@localhost ~]# nslookup www.baidu.com Server: 172.16.12.2 Address: 172.16.12.2#53 Non-authoritative answer: www.baidu.com canonical name = www.a.shifen.com. Name: www.a.shifen.com Address: 119.75.213.61 Name: www.a.shifen.com Address: 119.75.216.20
6.3 traceroute
traceroute命令用于路由跟踪, 检测网络故障出现在ISP运营商或是对端服务无法响应
[root@localhost ~]# traceroute www.baidu.com traceroute to www.baidu.com (182.61.200.7), 30 hops max, 60 byte packets 1 gateway (192.168.124.2) 0.134 ms 0.100 ms 0.065 ms 2 * * * 3 * * * 4 * * * 5 * * * 6 * * *
6.4 netstat
netstat用于查看网络状态
//常用选项 -antlp [root@localhost ~]# netstat -antlp Active Internet connections (servers and established) Proto Recv-Q Send-Q Local Address Foreign Address State PID/Program name tcp 0 0 0.0.0.0:22 0.0.0.0:* LISTEN 1096/sshd tcp 0 0 127.0.0.1:25 0.0.0.0:* LISTEN 1317/master tcp 0 196 192.168.124.134:22 192.168.124.1:57661 ESTABLISHED 1427/sshd: root@pts tcp6 0 0 :::22 :::* LISTEN 1096/sshd tcp6 0 0 ::1:25 :::* LISTEN 1317/master
6.5 ss
ss是一种网络状态查看工具,取代netstat
//语法:ss [options] [ FILTER ] //常用的options: -t:tcp协议相关 -u:udp协议相关 -w:裸套接字相关 -x:unix套接字相关 -l:listen状态的连接 -a:所有 -n:数字格式 -p:相关的程序及pid -e:扩展的信息 -m:内存用量 -o:显示计时器信息 //常见的FILTER: FILTER := [ state TCP-STATE ] [ EXPRESSION ] 如:ss -tan state ESTABLISHED //常见的state: //tcp finite state machine:有限状态机 LISTEN:监听 ESTABLISHED:已建立的连接 //EXPRESSION: dport = sport = 示例:'( dport = :ssh or sport = :ssh)',此处的ssh也即服务名可以使用其对应的端口号代替,等号两边必须有空格 //常用组合: [root@localhost ~]# ss -antlp State Recv-Q Send-Q Local Address:Port Peer Address:Port LISTEN 0 128 *:22 *:* users:(("sshd",pid=1096,fd=3)) LISTEN 0 100 127.0.0.1:25 *:* users:(("master",pid=1317,fd=13)) LISTEN 0 128 :::22 :::* users:(("sshd",pid=1096,fd=4)) LISTEN 0 100 ::1:25 :::* users:(("master",pid=1317,fd=14))
6.6 网络故障排查
网络故障分为硬件/软件故障
网卡损坏
链路故障
网卡驱动不兼容
网络排查思路
ping本地回环口, 确定本机TCP/IP协议栈是否正常
ping本机IP地址, 确定本地设备以及驱动是否正常
ping同网段主机, 确定二层网络是否正常工作
ping网关地址, 确定本地与网络是否正常
ping公网地址, 确定本地路由是否正常
ping公网域名, 确定DNS客户端是否正常
服务故障排查思路
使用telnet检测端口是否开放
检查服务端防火墙以及SElinux
检查相应的权限是否配置正常
检查日志是否有异常
检查完毕后持续测试