网络服务基础--协议和端口--路由和网关

柔光的暖阳◎ 2022-01-09 13:17 295阅读 0赞

# 一、常见网络协议和端口 #

## 1.网络地址和物理地址的概念 ##

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## 2. tcp/ip五层常见协议： ##

**应用层协议**：FTP、HTTP、SMTP、Telnet、DNS等 【**运维工程师必须要掌握的协议**】

**传输层协议**：TCP（可靠的、面向连接的传输协议）、UDP（不可靠的、面向无连接的传输协议）等【*各自有自己的应用场景、凡存在皆有理、不存在好坏之分*】  
**网络层协议**：IP（互联网协议）、ICMP（互联网控制消息协议）、ARP（地址解析协议，ip翻译成mac地址）等  
**数据链路层协议**：PPP协议（点对点拨号协议）等  
**物理层**：不常用（光电传输等知识）

## 3. 常见网络端口： ##

端口配置文件：/etc/service  
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/etc/service文件内容：

# /etc/services:
    # $Id: services,v 1.48 2009/11/11 14:32:31 ovasik Exp $
    #
    # Network services, Internet style
    # IANA services version: last updated 2009-11-10
    #
    # Note that it is presently the policy of IANA to assign a single well-known
    # port number for both TCP and UDP; hence, most entries here have two entries
    # even if the protocol doesn't support UDP operations.
    # Updated from RFC 1700, ``Assigned Numbers'' (October 1994).  Not all ports
    # are included, only the more common ones.
    #
    # The latest IANA port assignments can be gotten from
    #       http://www.iana.org/assignments/port-numbers
    # The Well Known Ports are those from 0 through 1023.
    # The Registered Ports are those from 1024 through 49151
    # The Dynamic and/or Private Ports are those from 49152 through 65535
    #
    # Each line describes one service, and is of the form:
    #
    # service-name  port/protocol  [aliases ...]   [# comment]
    
    tcpmux          1/tcp                           # TCP port service multiplexer
    tcpmux          1/udp                           # TCP port service multiplexer
    rje             5/tcp                           # Remote Job Entry
    rje             5/udp                           # Remote Job Entry
    echo            7/tcp
    echo            7/udp
    discard         9/tcp           sink null
    discard         9/udp           sink null
    systat          11/tcp          users
    systat          11/udp          users
    daytime         13/tcp
    daytime         13/udp
    qotd            17/tcp          quote
    qotd            17/udp          quote
    msp             18/tcp                          # message send protocol
    msp             18/udp                          # message send protocol
    chargen         19/tcp          ttytst source
    chargen         19/udp          ttytst source
    ftp-data        20/tcp
    ftp-data        20/udp
    # 21 is registered to ftp, but also used by fsp
    ftp             21/tcp
    ftp             21/udp          fsp fspd
    ssh             22/tcp                          # The Secure Shell (SSH) Protocol
    ssh             22/udp                          # The Secure Shell (SSH) Protocol
    telnet          23/tcp
    telnet          23/udp
    # 24 - private mail system
    lmtp            24/tcp                          # LMTP Mail Delivery
    lmtp            24/udp                          # LMTP Mail Delivery

# 二、路由和网关 #

## 路由： ##

先了解路由器的作用：

*  1.不同网段数据转发（跨网段通信，可以连接不同的网段）
 *  .2.路由选择：  
    动态路由（自动选择）  
    静态路由（适合小型网络、适合局域网、网络设备较少的情况，可以人为手动配置）

下图为自己观看视频，听老师讲解所绘，正确性、严谨性、理论性、均欠缺，只为个人理解  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80MjE5MzQ4OQ_size_16_color_FFFFFF_t_70 2]

## 网关： ##

（具备路由的作用）

*  1.不同网段数据转发
 *  2.路由选择
 *  3.默认路由
 *  4.NAT转换（NAT地址表，将内外网进行转换，需要拆包地址，缺点：速度慢，优点：通过将私有ip转换成公网ip，可以上公网，节省了ip地址）

## 网关和路由的设置： ##

route -n 查看系统中的路由表信息

[root@oracle ~]# route -n 
    Kernel IP routing table
    Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
    192.168.197.0   0.0.0.0         255.255.255.0   U     1      0        0 eth0
    0.0.0.0         192.168.197.1   0.0.0.0         UG    0      0        0 eth0
    #0.0.0.0.0代表处理不了的目标地址，都会发送给网关地址192.168.192.1来处理，需要上公网，必须设置网关

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## 三、7层网络模型 ##

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