Linux - 网络
目录
配置文件
Debian 下的网卡配置文件/etc/network/interfaces
Debian下 DNS 配置文件/etc/resolv.conf
CentOS 网卡配置文件/etc/sysconfig/network-scripts/
常用命令
在 CentOS7官方 FAQ 中提到已经移除 ifconfig 和 netstat 所用软件包 net-tools，改用 ip 和 ss 命令(软件包 iproute)。
7. What have you done with ifconfig/netstat? The ifconfig and netstat utilities have been marked as deprecated in the man pages for CentOS 5
The ifconfig and netstat utilities have been marked as deprecated in the man pages for CentOS 5 and 6 for nearly a decade and Redhat made the decision to no longer install the net-tools package by default in CentOS 7. One reason to switch is that ifconfig does not show all details of ip addresses assigned to interfaces - use the ip command instead. The replacement utilities are ss and ip. If you really really need ifconfig and netstat back then you can yum install net-tools.
尽管已经剔除，在工作中 CentOS6 还是见得到，这类工具也需要掌握最基本的使用方法。
ifcong
ifconfig #查看接口信息
inet 是对应的 IP，netmask 为子网掩码，broadcast 是广播地址，ether 是 MAC 地址，RX packets 是收到了多少字节的包，TX packets 是发送了多少包，对应的 error 可能是丢弃或者是什么原因没传输成功。
[root@iZ2ze3excf14rd7l4rsgn3Z ~]# ifconfig
eth0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500
inet 172.17.241.36 netmask 255.255.240.0 broadcast 172.17.255.255
ether 00:16:3e:0c:1f:1a txqueuelen 1000 (Ethernet)
RX packets 70247083 bytes 9217052363 (8.5 GiB)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 64130399 bytes 11258594120 (10.4 GiB)
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
loop txqueuelen 1000 (Local Loopback)
RX packets 6744950 bytes 11121955004 (10.3 GiB)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 6744950 bytes 11121955004 (10.3 GiB)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0禁止/启动网卡
ifup
ifdown
nestat
netstat -pantu #查看网络连接信息
route
route -n #查看路由表，避免解析为主机名因此使用 -n
Destination 是你要请求的目标地址，Gateway 会将 Destination 的流量通过 Gateway 转发出去。
[root@iZ2ze3excf14rd7l4rsgn3Z ~]# route
Kernel IP routing table
Destination Gateway Genmask Flags Metric Ref Use Iface
default gateway 0.0.0.0 UG 0 0 0 eth0
link-local 0.0.0.0 255.255.0.0 U 1002 0 0 eth0
172.17.240.0 0.0.0.0 255.255.240.0 U 0 0 0 eth0
[root@iZ2ze3excf14rd7l4rsgn3Z ~]# route -n
Kernel IP routing table
Destination Gateway Genmask Flags Metric Ref Use Iface
0.0.0.0 172.17.255.253 0.0.0.0 UG 0 0 0 eth0
169.254.0.0 0.0.0.0 255.255.0.0 U 1002 0 0 eth0
172.17.240.0 0.0.0.0 255.255.240.0 U 0 0 0 eth0
[root@iZ2ze3excf14rd7l4rsgn3Z ~]#ss
ss -lntp
-t 查看所有 tcp 连接
-l 插件监听端口
-n 禁止 IP 解析
-p 查看对应进程
-a 查看所有 tcp、udp 信息
ip
使用方法
ip [ OPTIONS ] OBJECT { COMMAND | help }
[root@iZ2ze3excf14rd7l4rsgn3Z ~]# ip --help
Usage: ip [ OPTIONS ] OBJECT { COMMAND | help }
ip [ -force ] -batch filename
where OBJECT := { link | address | addrlabel | route | rule | neigh | ntable |
tunnel | tuntap | maddress | mroute | mrule | monitor | xfrm |
netns | l2tp | fou | macsec | tcp_metrics | token | netconf | ila |
vrf }
OPTIONS := { -V[ersion] | -s[tatistics] | -d[etails] | -r[esolve] |
-h[uman-readable] | -iec |
-f[amily] { inet | inet6 | ipx | dnet | mpls | bridge | link } |
-4 | -6 | -I | -D | -B | -0 |
-l[oops] { maximum-addr-flush-attempts } | -br[ief] |
-o[neline] | -t[imestamp] | -ts[hort] | -b[atch] [filename] |
-rc[vbuf] [size] | -n[etns] name | -a[ll] | -c[olor]}
其中 OBJECT 里面的内容是有子功能
像是 ip address 执行后只显示简单网卡内容。
[root@iZ2ze3excf14rd7l4rsgn3Z ~]# ip address
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000
link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
inet 127.0.0.1/8 scope host lo
valid_lft forever preferred_lft forever
2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP group default qlen 1000
link/ether 00:16:3e:0c:1f:1a brd ff:ff:ff:ff:ff:ff
inet 172.17.241.36/20 brd 172.17.255.255 scope global dynamic eth0
valid_lft 284021179sec preferred_lft 284021179sec但在 man 中 SEE ALSO 章节还有许多介绍，其中 ip-address 还会有许多使用方法。
SEE ALSO
ip-address(8), ip-addrlabel(8), ip-l2tp(8), ip-link(8), ip-maddress(8), ip-monitor(8), ip-mroute(8), ip-neighbour(8), ip-netns(8), ip-ntable(8), ip-route(8), ip-rule(8),
ip-tcp_metrics(8), ip-token(8), ip-tunnel(8), ip-xfrm(8)
IP Command reference ip-cref.ps最简单就是使用 help 命令查看帮忙
[root@iZ2ze3excf14rd7l4rsgn3Z ~]# ip address help
Usage: ip address {add|change|replace} IFADDR dev IFNAME [ LIFETIME ]
[ CONFFLAG-LIST ]
ip address del IFADDR dev IFNAME [mngtmpaddr]
ip address {save|flush} [ dev IFNAME ] [ scope SCOPE-ID ]
[ to PREFIX ] [ FLAG-LIST ] [ label LABEL ] [up]
ip address [ show [ dev IFNAME ] [ scope SCOPE-ID ] [ master DEVICE ]
[ type TYPE ] [ to PREFIX ] [ FLAG-LIST ]
[ label LABEL ] [up] [ vrf NAME ] ]
ip address {showdump|restore}
IFADDR := PREFIX | ADDR peer PREFIX
[ broadcast ADDR ] [ anycast ADDR ]
[ label IFNAME ] [ scope SCOPE-ID ]
SCOPE-ID := [ host | link | global | NUMBER ]
FLAG-LIST := [ FLAG-LIST ] FLAG
FLAG := [ permanent | dynamic | secondary | primary |
[-]tentative | [-]deprecated | [-]dadfailed | temporary |
CONFFLAG-LIST ]
CONFFLAG-LIST := [ CONFFLAG-LIST ] CONFFLAG
CONFFLAG := [ home | nodad | mngtmpaddr | noprefixroute | autojoin ]
LIFETIME := [ valid_lft LFT ] [ preferred_lft LFT ]
LFT := forever | SECONDS
TYPE := { vlan | veth | vcan | dummy | ifb | macvlan | macvtap |
bridge | bond | ipoib | ip6tnl | ipip | sit | vxlan | lowpan |
gre | gretap | ip6gre | ip6gretap | vti | nlmon | can |
bond_slave | ipvlan | geneve | bridge_slave | vrf | hsr | macsec }每个命令通常有下面几种操作
add
delete
show/list
常用选项说明
-s，stats 显示状态信息
-h，human 讲一些数据显示为可读数据
-d，details 显示更多信息
-c，color 高亮显示
ntop
可以抓取网络流量，被DDOS的情况下可以用这个查看。
有开启一个Web端来查看信息。
ngrep
相当于一个抓取网络流量的 grep 工具
套餐
ngrep -W byline -d eth0 port 443tcpdump
一个命令行数据包分析工具，图形化可参见 Wireshark基本使用与网络协议简介 这篇文章。
Usages：tcpdump [options]
Options：
-i #网卡名
-s #为0不限制包内容
-w #保存为一个pcap包
-A #ASCII方式显示
-X #以十六进制方式显示
-r #读取一个pcap包
-V #读取一个文件列表
-n #不把地址转换为域名Example：
#筛选器
src host address #只显示指定source地址
dst host address #只显示指定destination地址
[协议类型] port port_number #筛选你要的协议或端口参考链接
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