首先介绍最基本也是经常用到的命令ifconfig，对应windows中的ipconfig。执行ifconfig会将所有的端口信息都显示出来，包括IP地址，MTU 接收和发送的报文还有HWaddr也就是MAC地址root@zhf-linux:/home/zhf# ifconfigeth0 Link encap:Ethernet HWaddr 00:23:5a:b6:de:9f UP 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:820 errors:0 dropped:0 overruns:0 frame:0 TX packets:820 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1 RX bytes:66752 (66.7 KB) TX bytes:66752 (66.7 KB)wlan0 Link encap:Ethernet HWaddr 00:26:82:07:ef:3c inet addr:192.168.0.11 Bcast:192.168.0.255 Mask:255.255.255.0 inet6 addr: fe80::226:82ff:fe07:ef3c/64 Scope:Link UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 RX packets:10115 errors:0 dropped:0 overruns:0 frame:0 TX packets:5520 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000 RX bytes:6316755 (6.3 MB) TX bytes:686532 (686.5 KB)如果只是想列出某个端口的网络地址可以使用ifconfig wlan0的方法root@zhf-linux:/home/zhf# ifconfig wlan0wlan0 Link encap:Ethernet HWaddr 00:26:82:07:ef:3c inet addr:192.168.0.11 Bcast:192.168.0.255 Mask:255.255.255.0 inet6 addr: fe80::226:82ff:fe07:ef3c/64 Scope:Link UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 RX packets:10902 errors:0 dropped:0 overruns:0 frame:0 TX packets:6101 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000 RX bytes:6499772 (6.4 MB) TX bytes:773060 (773.0 KB)我们还可以通过ifconfig来修改这些网络的相关信息。修改MTU信息：root@zhf-linux:/home/zhf# ifconfig wlan0 mtu 1400wlan0 Link encap:Ethernet HWaddr 00:26:82:07:ef:3c inet addr:192.168.0.11 Bcast:192.168.0.255 Mask:255.255.255.0 inet6 addr: fe80::226:82ff:fe07:ef3c/64 Scope:Link UP BROADCAST RUNNING MULTICAST MTU:1400 Metric:1 RX packets:11902 errors:0 dropped:0 overruns:0 frame:0 TX packets:6912 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000 RX bytes:7099710 (7.0 MB) TX bytes:864672 (864.6 KB)修改端口的IP地址root@zhf-linux:/home/zhf# ifconfig eth0 192.168.0.15如果时候ifconfig错误的修改了网络佩之，可以通过/etc/init.d/networking restart的方式来重新启动某个网口，之前手动的设置数据会全部失效。如果我使用的是无线网卡，查看具体的无线网络信息通过iwconfig命令root@zhf-linux:/home/zhf# iwconfigwlan0 IEEE 802.11bg ESSID:"zhf_dxx" Mode:Managed Frequency:2.462 GHz Access Point: A4:56:02:4D:65:1F Bit Rate=18 Mb/s Tx-Power=20 dBm Retry short limit:7 RTS thr:off Fragment thr:off Encryption key:off Power Management:off Link Quality=70/70 Signal level=-3 dBm Rx invalid nwid:0 Rx invalid crypt:0 Rx invalid frag:0 Tx excessive retries:330 Invalid misc:735 Missed beacon:0路由信息：上网除了配置IP地址等信息外，路由也是一个关键的因素。路由顾名思义就是如何转发数据包的依据。route命令可以查看当前服务器的信息。Destinaton和Genmask分别是网络地址与网络掩码。第一条路由信息中Destination是default， Genmask是0.0.0.0. 可以认为是全网路由，也就是可以达到任务的网络地址。Gateway就是网关，从当前服务器出去的数据都是通过网关地址设备来进行转发。这里网关地址为192.168.0.1也就是无线路由器的地址。Flags: 路由的标识。 U表示路由是启动的。H目标是一台主机而非网络 。G：需要通过外部的主机来传递数据包。R：动态路由。 D：动态路由。M：路由被修改了Iface：路由传递数据报的接口root@zhf-linux:/home/zhf# routeKernel IP routing tableDestination Gateway Genmask Flags Metric Ref Use Ifacedefault 192.168.0.1 0.0.0.0 UG 600 0 0 wlan0link-local * 255.255.0.0 U 1000 0 0 wlan0192.168.0.0 * 255.255.255.0 U 600 0 0 wlan0我们还可以手动添加和删除路由：添加的时候需要设置-net 目标网络地址，netmask 网络掩码 gw：网关root@zhf-linux:/home/zhf# route add -net 192.168.1.0 netmask 255.255.255.0 gw 192.168.0.1root@zhf-linux:/home/zhf# route add -net 192.168.1.0 netmask 255.255.255.0 gw 192.168.0.1root@zhf-linux:/home/zhf# routeKernel IP routing tableDestination Gateway Genmask Flags Metric Ref Use Ifacedefault 192.168.0.1 0.0.0.0 UG 600 0 0 wlan0link-local * 255.255.0.0 U 1000 0 0 wlan0192.168.0.0 * 255.255.255.0 U 600 0 0 wlan0192.168.1.0 192.168.0.1 255.255.255.0 UG 0 0 0 wlan0删除的时候可以不带网关地址。root@zhf-linux:/home/zhf# route del -net 192.168.1.0 netmask 255.255.255.0root@zhf-linux:/home/zhf# routeKernel IP routing tableDestination Gateway Genmask Flags Metric Ref Use Ifacedefault 192.168.0.1 0.0.0.0 UG 600 0 0 wlan0link-local * 255.255.0.0 U 1000 0 0 wlan0192.168.0.0 * 255.255.255.0 U 600 0 0 wlan0下面介绍一个综合前面route 和ifconfig的命令:ip. 主要有几个参数;-s:显示出设备的统计数据，如接收数据包的总数等link: 与设备相关的设置，包括MTU，Mac地址等addr/address:关于额外的IP协议route: 与路由有关的相关设置比如ip link show显示所有端口的硬件信息root@zhf-linux:/home/zhf# ip link show1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN mode DEFAULT group default qlen 1 link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:002: eth0: <NO-CARRIER,BROADCAST,MULTICAST,UP> mtu 1500 qdisc pfifo_fast state DOWN mode DEFAULT group default qlen 1000 link/ether 00:23:5a:b6:de:9f brd ff:ff:ff:ff:ff:ff3: wlan0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc mq state UP mode DORMANT group default qlen 1000 link/ether 00:26:82:07:ef:3c brd ff:ff:ff:ff:ff:ff还可以通过ip link set eth0 up/ip link set eth0 down来启动和关闭端口还可以修改端口的名称，但首先要关闭这个端口。否则无法修改root@zhf-linux:/home/zhf# ip link set eth0 name zhfRTNETLINK answers: Device or resource busyroot@zhf-linux:/home/zhf# ip link set eth0 downroot@zhf-linux:/home/zhf# ip link set eth0 name zhfroot@zhf-linux:/home/zhf# ip link show1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN mode DEFAULT group default qlen 1 link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:002: zhf: <BROADCAST,MULTICAST> mtu 1500 qdisc pfifo_fast state DOWN mode DEFAULT group default qlen 1000 link/ether 00:23:5a:b6:de:9f brd ff:ff:ff:ff:ff:ff3: wlan0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc mq state UP mode DORMANT group default qlen 1000 link/ether 00:26:82:07:ef:3c brd ff:ff:ff:ff:ff:ffip route添加路由root@zhf-linux:/home/zhf# ip route add 192.168.5.0/24 dev eth0root@zhf-linux:/home/zhf# routeKernel IP routing tableDestination Gateway Genmask Flags Metric Ref Use Ifacedefault 192.168.0.1 0.0.0.0 UG 600 0 0 wlan0link-local * 255.255.0.0 U 1000 0 0 wlan0192.168.0.0 * 255.255.255.0 U 600 0 0 wlan0192.168.5.0 * 255.255.255.0 U 0 0 0 eth0接着介绍几个网络定位的命令。 首先来看用到最多的命令pingping的参数如下;-c 后面接ping的次数 -s ping报文的大小-t TTL的数值-W：等待响应对方主机的秒数-M：主要检测网络的MTU数值大小比如ping 5次新浪网。从第一行可以看到ping包的字节默认为56个字节，加上28个字节的头信息root@zhf-linux:/home/zhf# ping -c 5 www.sina.com.cnPING www.sina.com.cn (218.30.66.248) 56(84) bytes of data.64 bytes from www.sina.com.cn (218.30.66.248): icmp_seq=1 ttl=54 time=19.8 ms64 bytes from www.sina.com.cn (218.30.66.248): icmp_seq=2 ttl=54 time=19.2 ms64 bytes from www.sina.com.cn (218.30.66.248): icmp_seq=3 ttl=54 time=22.0 ms64 bytes from www.sina.com.cn (218.30.66.248): icmp_seq=4 ttl=54 time=33.3 ms64 bytes from www.sina.com.cn (218.30.66.248): icmp_seq=5 ttl=54 time=21.8 ms--- www.sina.com.cn ping statistics ---5 packets transmitted, 5 received, 0% packet loss, time 4005msrtt min/avg/max/mdev = 19.202/23.265/33.306/5.144 ms改变ping包字节大小为120字节。加上头信息为148字节root@zhf-linux:/home/zhf# ping -c 5 -s 120 www.sina.com.cnPING www.sina.com.cn (218.30.66.248) 120(148) bytes of data.128 bytes from www.sina.com.cn (218.30.66.248): icmp_seq=1 ttl=54 time=19.5 ms128 bytes from www.sina.com.cn (218.30.66.248): icmp_seq=2 ttl=54 time=22.7 ms128 bytes from www.sina.com.cn (218.30.66.248): icmp_seq=3 ttl=54 time=18.8 ms128 bytes from www.sina.com.cn (218.30.66.248): icmp_seq=4 ttl=54 time=45.0 ms128 bytes from www.sina.com.cn (218.30.66.248): icmp_seq=5 ttl=54 time=18.0 ms--- www.sina.com.cn ping statistics ---5 packets transmitted, 5 received, 0% packet loss, time 4006msrtt min/avg/max/mdev = 18.062/24.846/45.060/10.230 ms我们可以根据ping 命令来写一个探测网络内存在的主机：for siteip in $(seq 1 254) do site="192.168.1.${siteip}" ping -c 2 ${site} &>/dev/null if [ "$?" == 0 ];then echo "$site is up" else echo "$site is down" fi doneroot@zhf-linux:/home/zhf/zhf/shell_prj# sh ping_test.sh192.168.1.1 is up192.168.1.2 is up192.168.1.3 is down192.168.1.4 is down192.168.1.5 is down192.168.1.6 is down192.168.1.7 is downping命令虽然能检测链路是否通，但是网络传输中会经过很多个网络节点。如果不通的话数据包是在哪个网络节点遇到故障了呢，这个时候就需要用到traceroute命令。主要参数如下;-n: 不必进行主机的名称解析，单纯用IP-U：使用UDP的port 33434进行检测。这是Linux默认的协议。windows是采用ICMP-I：使用ICMP的方式进行检测-T：使用TCP进行检测-w: 设置等待对方响应的时间-p：端口号可以看到traceroute会显示经过的每个节点的IP以及所消耗的时延。这样就十分便于我们定位问题到底出在哪root@zhf-linux:/home/zhf/zhf/shell_prj# traceroute -n www.sina.com.cntraceroute to www.sina.com.cn (218.30.66.248), 30 hops max, 60 byte packets 1 192.168.1.1 4.485 ms 4.505 ms 4.578 ms 2 100.64.0.1 8.041 ms 8.262 ms 10.867 ms 3 100.64.0.1 11.015 ms 11.144 ms 11.284 ms 4 220.167.87.17 19.405 ms 19.595 ms 19.651 ms 5 171.208.203.69 22.509 ms 171.208.203.57 22.172 ms 22.257 ms 6 202.97.48.125 35.747 ms 202.97.48.117 36.414 ms 202.97.48.125 30.744 ms 7 218.30.19.94 37.071 ms 218.30.69.2 25.474 ms 218.30.19.94 38.695 ms^Croot@zhf-linux:/home/zhf/zhf/shell_prj# traceroute www.sina.com.cntraceroute to www.sina.com.cn (218.30.66.248), 30 hops max, 60 byte packets 1 192.168.1.1 (192.168.1.1) 7.411 ms 7.513 ms 7.563 ms 2 100.64.0.1 (100.64.0.1) 8.165 ms 8.451 ms 8.686 ms 3 100.64.0.1 (100.64.0.1) 9.012 ms 9.000 ms 9.268 ms 4 220.167.87.17 (220.167.87.17) 48.949 ms 49.123 ms 49.170 ms 5 171.208.203.69 (171.208.203.69) 10.046 ms 171.208.203.57 (171.208.203.57) 9.840 ms 171.208.198.25 (171.208.198.25) 13.523 ms 6 202.97.48.125 (202.97.48.125) 34.782 ms 26.170 ms 202.97.48.117 (202.97.48.117) 31.479 ms 7 218.30.69.2 (218.30.69.2) 22.882 ms 218.30.19.94 (218.30.19.94) 31.512 ms 218.30.69.2 (218.30.69.2) 23.094 ms即使有了traceroute命令，我们也只是知道问题是出在哪。但是问题的根因是什么我们还是不知道。很多时候需要抓包进行问题分析。这时候就要用到tcpdump命令。tcpdump不但可以分析数据包的流向，而且连数据包的内容也可以进行监听关键参数如下：-A: 数据包的内容以ASCII显示-e:使用数据链路层MAC数据包数据来显示-nn:直接以IP及port number显示-q:仅列出简短的数据信息-X：列出十六进制以及ASCII的数据包内容-i: 要监听的网络接口 例如eth0,lo,wlan等-w: 如果你要将监听所得的数据包数据存储下来，后面接文件名-r:从后面的文件将数据包数据读出来抓取wlan0端口的数据并存储到test1.txt文件中。tcpdump -i wlan0 -nn -X > test1.txt21:48:06.869312 IP 180.149.136.194.80 > 192.168.0.11.50592: Flags [S.], seq 3280367214, ack 1401941542, win 14600, options [mss 1440,nop,nop,sackOK,nop,wscale 7], length 0 0x0000: 4500 0034 475e 0000 3706 3e5b b495 88c2 E..4G^..7.>[.... 0x0010: c0a8 000b 0050 c5a0 c386 6e6e 538f ee26 .....P....nnS..& 0x0020: 8012 3908 fe65 0000 0204 05a0 0101 0402 ..9..e.......... 0x0030: 0103 0307 ....21:48:06.869360 IP 192.168.0.11.50592 > 180.149.136.194.80: Flags [.], ack 1, win 229, length 0 0x0000: 4500 0028 ae0b 4000 4006 8eb9 c0a8 000b E..(..@.@....... 0x0010: b495 88c2 c5a0 0050 538f ee26 c386 6e6f .......PS..&..no 0x0020: 5010 00e5 7747 0000 P...wG..21:48:06.870044 IP 192.168.0.11.50592 > 180.149.136.194.80: Flags [.], seq 1:1441, ack 1, win 229, length 1440: HTTP: GET /mfp/view?type=3&t=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&userid=222.210.164.210_1448460046.241583&viewlog=false&hashCode=3400c1d3fbc463e290cf234cd786ceed&_sinaads_sio_log_ivciiq HTTP/1.1由于数据较多，可以将数据内容都存在文件中，后面来查看。cap文件可以用wireshark软件打开。root@zhf-linux:/home/zhf/zhf# tcpdump -i wlan0 -w tcpdump_test.cap想监听某一个端口，比如监控网页的数据。可以指定端口root@zhf-linux:/home/zhf/zhf# tcpdump -i wlan0 -nn port 8080
转载于:https://www.cnblogs.com/zhanghongfeng/p/7689300.html
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