01 – Linux虚拟机出现多个默认路由，导致部分网络连接异常
# route -n
Kernel IP routing table
Destination Gateway Genmask Flags Metric Ref Use Iface
0.0.0.0 192.168.16.1 0.0.0.0 UG 100 0 0 enp0s3
0.0.0.0 10.0.3.2 0.0.0.0 UG 101 0 0 enp0s8
......
处理方法：更改网关192.168.16.1的路由设置。
- CentOS7：应用程序—》系统工具—》设置—》网络—》以太网（enp0s3），点击右下角的设置按钮—》IPv4—》选择“仅对此网络上的资源使用此连接”—》应用。
- Ubuntu1604：系统设置—》网络—》有线，选择对应网卡—》选项—》IPv4设置—》路由—》选择“仅将此连接用于相对应的网络上的资源”—》确定。
# route -n
......
192.168.16.0 0.0.0.0 255.255.255.0 U 100 0 0 enp0s3
......
02 – Linux查看端口状态
检测本机8080端口状态：netstat –apn | grep 8080
检测192.168.0.1主机的8080端口状态：telnet 192.168.0.1 8080 或nmap -sS -P0 -n -p 22 192.168.0.1
检测192.168.0.1主机的1到1024端口状态：nc -z 192.168.0.1 1-1024
# nmap -sS -P0 -n -p 22 10.140.0.135
Starting Nmap 6.40 ( http://nmap.org ) at 2016-11-09 10:42 CST
Nmap scan report for 10.140.0.135
Host is up (0.00040s latency).
PORT STATE SERVICE
22/tcp open ssh
MAC Address: 08:00:27:3F:19:79 (Cadmus Computer Systems)
Nmap done: 1 IP address (1 host up) scanned in 0.07 seconds# nmap -sS -P0 -n -p 80 10.140.0.135
Starting Nmap 6.40 ( http://nmap.org ) at 2016-11-09 10:50 CST
Nmap scan report for 10.140.0.135
Host is up (0.00046s latency).
PORT STATE SERVICE
80/tcp closed http
MAC Address: 08:00:27:3F:19:79 (Cadmus Computer Systems)
Nmap done: 1 IP address (1 host up) scanned in 0.06 seconds
03 – Linux命令行设置CentOS计算机名称、hosts及网卡地址
$ echo "anliven" > /etc/hostname
$ echo -e "192.168.16.166 master\n192.168.16.167 slave01\n192.168.16.168 slave02" >> /etc/hosts
$ sed -i '/IPADDR/s/192.168.16.200/192.168.16.166/' /etc/sysconfig/network-scripts/ifcfg-enp0s8
$ reboot
04 – Linux CentOS7关闭SELinux
- 永久方法：修改/etc/selinux/config文件中设置SELINUX=disabled ，然后重启。
# getenforce
Enforcing
# sed -i '/SELINUX/s/enforcing/disabled/' /etc/selinux/config
# reboot
- 临时方法：执行
setenforce 0命令设置SELinux成为permissive模式
sudo systemctl status firewalld.service
sudo systemctl stop firewalld.service
sudo systemctl disable firewalld.service
05 – Ubuntu安装ssh并允许root登录
- Install openssh-server
apt-get update
apt-get install openssh-server
- Change ssh configuration
root@anliven:~# vim /etc/ssh/sshd_config
root@anliven:~#
root@anliven:~# cat /etc/ssh/sshd_config |grep RootLogin
#PermitRootLogin without-password
PermitRootLogin yes
# the setting of "PermitRootLogin without-password".
root@anliven:~#
root@anliven:~# /etc/init.d/ssh restart
ssh stop/waiting
ssh start/running, process 3782
root@anliven:~#
- Check ssh status
root@anliven:~# lsof -i:22
COMMAND PID USER FD TYPE DEVICE SIZE/OFF NODE NAME
sshd 3630 root 3u IPv4 19611 0t0 TCP *:ssh (LISTEN)
sshd 3630 root 4u IPv6 19613 0t0 TCP *:ssh (LISTEN)
root@anliven:~#
root@anliven:~# ps -ef |grep ssh
root 3630 1 0 13:43 ? 00:00:00 /usr/sbin/sshd -D
root 3750 3732 0 13:46 pts/1 00:00:00 grep --color=auto ssh
root@anliven:~#
06 – Linux常用网络软件包
- inetuils-ping — ping
- net-tools — ifconfig/route/netstat/……
- iproute — ip
- traceroute
- bind-utils — nslookup/dig/host/……
- bridge-utils — brctl
- nmap
- tcpdump
- wireshark
- curl
- wget
……
07 – Linux设置ssh免密码认证
示例：slave01和slave02两个主机ssh免密码相互登录
### 设置slave01 node
[hadoop@slave01 ~]$ ssh-keygen
[hadoop@slave01 ~]$
[hadoop@slave01 ~]$ cd .ssh
[hadoop@slave01 .ssh]$ ssh-copy-id -i hadoop@slave01
[hadoop@slave01 .ssh]$ ssh-copy-id -i hadoop@slave02
[hadoop@slave01 .ssh]$
[hadoop@slave01 .ssh]$ ll -a
total 20
drwx------ 2 hadoop hadoop 76 Mar 7 23:34 .
drwx------. 6 hadoop hadoop 4096 Mar 7 23:30 ..
-rw------- 1 hadoop hadoop 1187 Mar 7 23:34 authorized_keys
-rw------- 1 hadoop hadoop 1675 Mar 7 23:33 id_rsa
-rw-r--r-- 1 hadoop hadoop 396 Mar 7 23:33 id_rsa.pub
-rw-r--r-- 1 hadoop hadoop 551 Mar 7 23:34 known_hosts
[hadoop@slave01 .ssh]$ ### 设置slave02 node
[hadoop@slave02 ~]$ ssh-keygen
[hadoop@slave02 ~]$
[hadoop@slave02 ~]$ cd .ssh
[hadoop@slave02 .ssh]$ ssh-copy-id -i hadoop@slave01
[hadoop@slave02 .ssh]$ ssh-copy-id -i hadoop@slave02
[hadoop@slave02 .ssh]$
[hadoop@slave02 .ssh]$ ll -a
total 20
drwx------ 2 hadoop hadoop 76 Mar 7 23:35 .
drwx------. 6 hadoop hadoop 4096 Mar 7 23:30 ..
-rw------- 1 hadoop hadoop 1187 Mar 7 23:35 authorized_keys
-rw------- 1 hadoop hadoop 1675 Mar 7 23:33 id_rsa
-rw-r--r-- 1 hadoop hadoop 396 Mar 7 23:33 id_rsa.pub
-rw-r--r-- 1 hadoop hadoop 551 Mar 7 23:35 known_hosts
[hadoop@slave01 .ssh]$
08 – Linux设置路由并指定metric值
- 默认路由：route add default gw 10.0.2.2 metric 1
- 指定路由：route add 192.168.0.0 mask 255.255.0.0 192.168.16.1 metric 10
