[Linux 文章收集] Centos7 的 ifconfig 和 netstat

Source From Here 
Preface 
Centos7/RHEL 7 的 ifconfig, netstat, route 和 traceroute 都不見了，其實 Centos6 就已經有一些變革，只是 netstat 和 ifconfig 那時還保留著，所以沒發現. Centos7 和RHEL 7 最小安裝中竟然沒有我最常用的 ifconfig 和 netstat？ 

# ifconfig
-bash: ifconfig: command not found

很好，原來centos/rhel準備把這兩個指令作廢，那怎麼辦？一是安裝，二是改用別的指令。 

安裝 
yum 有提供一個尋找程式所屬套件的方法: 

# yum provides ifconfig
Loaded plugins: fastestmirror
Loading mirror speeds from cached hostfile
* base: centos.unixheads.org
* epel: mirror.steadfast.net
* extras: mirrors.liquidweb.com
* updates: mirrors.advancedhosters.com
net-tools-2.0-0.22.20131004git.el7.x86_64 : Basic networking tools
Repo : @base
Matched from:
Filename : /usr/sbin/ifconfig

# yum whatprovides ifconfig
Loaded plugins: fastestmirror
Loading mirror speeds from cached hostfile
* base: centos.unixheads.org
* epel: mirror.steadfast.net
* extras: mirrors.liquidweb.com
* updates: mirrors.lga7.us.voxel.net
net-tools-2.0-0.22.20131004git.el7.x86_64 : Basic networking tools
Repo : @base
Matched from:
Filename : /usr/sbin/ifconfig

# yum install net-tools // 安裝 infconfig
# yum install traceroute // 安裝 traceroute

這樣裝完就有 ifconfig, netstat 和 route 以及 traceroute 和 traceroute6. 

改用別的指令 
其實 ifconfig 在 7 版中全部有新指令代替，所以可能要學習新的方法。 

ifconfig 改用 ip addr 

$ ip addr // 這個和 ifconfig 顯示的一樣

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1. 1: lo: mtu 65536 qdisc noqueue state UNKNOWN  
2.     link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00  
3.     inet 127.0.0.1/8 scope host lo  
4.        valid_lft forever preferred_lft forever  
5.     inet6 ::1/128 scope host  
6.        valid_lft forever preferred_lft forever  
7. 2: ens192: mtu 1500 qdisc pfifo_fast state UP qlen 1000  
8.     link/ether 00:50:56:ba:0b:07 brd ff:ff:ff:ff:ff:ff  
9.     inet 163.17.xx.xx/25 brd 163.17.40.127 scope global ens192  
10.        valid_lft forever preferred_lft forever  
11.     inet6 2001:288:5400:0:250:56ff:feba:b07/64 scope global dynamic  
12.        valid_lft 2591718sec preferred_lft 2591718sec  
13.     inet6 fe80::250:56ff:feba:b07/64 scope link  
14.        valid_lft forever preferred_lft forever  

$ ip link // Show network device(s)

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1. 1: lo: mtu 65536 qdisc noqueue state UNKNOWN mode DEFAULT  
2.     link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00  
3. 2: ens192: mtu 1500 qdisc pfifo_fast state UP mode DEFAULT qlen 1000  
4.     link/ether 00:50:56:ba:0b:07 brd ff:ff:ff:ff:ff:ff  

// -s, -stats, -statistics: Output more information.
$ ip -s link

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1. 1: lo: mtu 65536 qdisc noqueue state UNKNOWN mode DEFAULT  
2.     link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00  
3.     RX: bytes  packets  errors  dropped overrun mcast  
4.     4400       45       0       0       0       0  
5.     TX: bytes  packets  errors  dropped carrier collsns  
6.     4400       45       0       0       0       0  
7. 2: ens192: mtu 1500 qdisc pfifo_fast state UP mode DEFAULT qlen 1000  
8.     link/ether 00:50:56:ba:0b:07 brd ff:ff:ff:ff:ff:ff  
9.     RX: bytes  packets  errors  dropped overrun mcast  
10.     207938930  2541628  0       1809366 0       495  
11.     TX: bytes  packets  errors  dropped carrier collsns  
12.     788417     8512     0       0       0       0  

netstat 改用 ss 
netstat 是很重要的連線觀察工具，使用新的指令 ss 來取代，功能也是差不多: 

// -l, --listening: Display only listening sockets (these are omitted by default).
// -t, --tcp: Display TCP sockets.
# ss -lt

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1. State       Recv-Q Send-Q Local Address:Port                 Peer Address:Port           
2. LISTEN      0      128           *:ssh                         *:*  
3. LISTEN      0      128    127.0.0.1:postgres                    *:*  
4. LISTEN      0      100    127.0.0.1:smtp                        *:*  
5. LISTEN      0      128          :::ssh                        :::*  
6. LISTEN      0      128         ::1:postgres                   :::*  
7. LISTEN      0      100         ::1:smtp                       :::*  

// -u, --udp: Display UDP sockets.
# ss -lu

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1. State       Recv-Q Send-Q Local Address:Port                 Peer Address:Port           
2. UNCONN      0      0             *:bootpc                      *:*  
3. UNCONN      0      0      x.x.x.x:ntp                         *:*                     
4. UNCONN      0      0      127.0.0.1:ntp                         *:*  
5. UNCONN      0      0             *:ntp                         *:*  
6. UNCONN      0      0             *:mdns                        *:*  
7. UNCONN      0      0             *:59433                       *:*  
8. UNCONN      0      0             *:39254                       *:*  
9. UNCONN      0      0            :::60817                      :::*  
10. UNCONN      0      0           ::1:ntp                        :::*  
11. UNCONN      0      0            :::ntp                        :::*  

traceroute/traceroute6 改成 tracepath 

$ tracepath 168.95.1.1

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1. 1:  163.17.XX.XX                                          0.187ms pmtu 1500  
2. 1:  163.17.40.126                                         0.263ms  
3. 2:  163.17.38.250                                         0.555ms  
4. 3:  br-NCHU-APTG.TANet.edu.tw                            19.799ms  
5. 4:  no reply  
6. 5:  tchn-3302.hinet.net                                   1.395ms asymm  6  
7. 6:  tchn-3011.hinet.net                                  15.089ms  
8. 7:  202-39-179-185.HINET-IP.hinet.net                     1.533ms  
9. 8:  202-39-179-173.HINET-IP.hinet.net                     4.435ms reached  
10.     Resume: pmtu 1500 hops 8 back 248  

route 改為 ip route 

$ ip route show
192.168.91.0/24 dev eth0 proto kernel scope link src 192.168.91.128
169.254.0.0/16 dev eth0 scope link metric 1002
default via 192.168.91.2 dev eth0

介面開關 

$ ip link set eth1 up # Or ip l set eth1 up
$ ip link set eth1 down # Or ip l set eth1 down

Supplement 
* Linux 文章收集 - 10 Useful “IP” Commands to Configure Network Interfaces