2018.5.8 seven weeks three lessons (FIREWALLD and Netfilter,iptables grammar)

Linux Network related CentOS version 6, if you want to use Ifconfig to install a net-tools

     [[email protected] ~]# yum install -y net-tools

Turn off a network card

    [[email protected] ~]# ifdown ens33

Turn on the NIC

    [[email protected] ~]# ifup ens33

Restart the NIC

    [[email protected] ~]# ifdown ens33 && ifup ens33

Add a virtual network card

    [[email protected] ~]# cd /etc/sysconfig/network-scripts/    [[email protected] network-scripts]# cp ifcfg-ens33 ifcfg-ens33\:0    #进入到配置文件，拷贝一份IP目录，然后修改名为ens33:0,这里的“\”是为了脱义冒号

Modify the configuration file for the virtual network card

    [[email protected] network-scripts]# vi ifcfg-ens33:0    这里就编辑三个地方就可以，NAME和DEVICE还有IP地址    然后重启网卡：    [[email protected] network-scripts]# ifdown ens33 && ifup ens33

Added successfully.

See if a network card is plugged in.

    [[email protected] network-scripts]# mii-tool ens33 #后面跟网卡的名字    ens33: negotiated 1000baseT-FD flow-control, link ok #看看后面是不是ok

Modify host name Hostnamectl Set-hostname zhang-01

    [[email protected] ~]# hostnamectl set-hostname zhang-01    [[email protected] ~]# bash #打开一个子shell看下是否修改成功    

DNS configuration file in/etc/resolv.conf

    [[email protected] ~]# cat /etc/resolv.conf     # Generated by NetworkManager    nameserver 119.29.29.29    nameserver 114.114.114.114

Firewalld and NetFilter (firewall)

Linux防火墙-netfilter：selinux临时关闭 setenforce 0 selinux永久关闭 vi /etc/selinux/config centos7之前使用netfilter防火墙 centos7开始使用firewalld防火墙 关闭firewalld开启netfilter方法 systemctl stop firewalld 服务关掉 systemctl disable firewalled 关闭firewalled 不让开机启动 yum install -y iptables-services 如果再开启firewalled需要安装一个包 systemctl enable iptables  systemctl start iptables 开启

Permanently shut down the firewall, edit the configuration file selinux=enforcing modify to Disabled

View Iptables Services

    [[email protected] ~]# iptables -nvL #可以查看里面默认的规则 5表5列

Linux firewall-netfilter

netfilter的5个表 filter表用于过滤包，最常用的表，有INPUT、FORWARD、OUTPUT三个链 nat表用于网络地址转换，有PREROUTING、OUTPUT、POSTROUTING三个链 managle表用于给数据包做标记，几乎用不到 raw表可以实现不追踪某些数据包，阿铭从来不用

2018.5.8 seven weeks three lessons (FIREWALLD and Netfilter,iptables grammar)