网络安全学习--VLAN

Posted 2022-01-04 丢爸

VLAN(Virtual LAN)虚拟局域网

VLAN属于2层技术

广播的危害

增加网络/终端负担，传播病毒，安全性

如何控制广播

控制广播=隔离广播域
路由器隔离广播(物理隔离广播)
路由器隔离广播缺点：成本高，不灵活
采用新的技术VLAN控制广播，VLAN技术是在交换机上实现且通过逻辑隔离划分的广播域。
一个VLAN=一个广播域=一个网段

VLAN类型

1. 静态VLAN
   • 手工配置
   • 基于端口划分的VLAN
2. 动态VLAN

• 手工配置
• 基于MAC地址划分的VLAN

vlan实验

默认交换机已经存在VLAN,所有的端口都属于vlan 1即default中，所以跨交换机中的PC在加入不同VLAN时，不做配置无法直接通信。

#-------------------------Switch0是配置信息-------------------
Switch>enable
Switch#configure terminal
Enter configuration commands, one per line.  End with CNTL/Z.

Switch(config)#vlan ?
  <1-4094>  ISL VLAN IDs 1-1005
Switch(config)#vlan 
% Incomplete command.
Switch(config)#vlan 10
Switch(config-vlan)#name first
Switch(config-vlan)#exit
Switch(config)#vlan 20
Switch(config-vlan)#name second
Switch(config-vlan)#exit
Switch(config)#do show vlan brief

VLAN Name                             Status    Ports
---- -------------------------------- --------- -------------------------------
1    default                          active    Fa0/1, Fa0/2, Fa0/3, Fa0/4
                                                Fa0/5, Fa0/6, Fa0/7, Fa0/8
                                                Fa0/9, Fa0/10, Fa0/11, Fa0/12
                                                Fa0/13, Fa0/14, Fa0/15, Fa0/16
                                                Fa0/17, Fa0/18, Fa0/19, Fa0/20
                                                Fa0/21, Fa0/22, Fa0/23, Fa0/24
                                                Gig0/1, Gig0/2
10   first                            active    
20   second                           active    
1002 fddi-default                     active    
1003 token-ring-default               active    
1004 fddinet-default                  active    
1005 trnet-default                    active   
Switch(config)#interface f0/2
Switch(config-if)#switchport access vlan 10
Switch(config-if)#exit
Switch(config)#interface f0/3
Switch(config-if)#switchport access vlan 20
Switch(config-if)#do show vlan brief

VLAN Name                             Status    Ports
---- -------------------------------- --------- -------------------------------
1    default                          active    Fa0/4, Fa0/5, Fa0/6, Fa0/7
                                                Fa0/8, Fa0/9, Fa0/10, Fa0/11
                                                Fa0/12, Fa0/13, Fa0/14, Fa0/15
                                                Fa0/16, Fa0/17, Fa0/18, Fa0/19
                                                Fa0/20, Fa0/21, Fa0/22, Fa0/23
                                                Fa0/24, Gig0/1, Gig0/2
10   first                            active    Fa0/1, Fa0/2
20   second                           active    Fa0/3
1002 fddi-default                     active    
1003 token-ring-default               active    
1004 fddinet-default                  active   
#-------------------------Switch0是配置信息-------------------
#-------------------------Switch1是配置信息-------------------

Switch#configure terminal
Enter configuration commands, one per line.  End with CNTL/Z.
Switch(config)#vlan 10
Switch(config-vlan)#exit
Switch(config)#vlan 20
Switch(config-vlan)#exit
Switch(config)#do show vlan brief

VLAN Name                             Status    Ports
---- -------------------------------- --------- -------------------------------
1    default                          active    Fa0/1, Fa0/2, Fa0/3, Fa0/4
                                                Fa0/5, Fa0/6, Fa0/7, Fa0/8
                                                Fa0/9, Fa0/10, Fa0/11, Fa0/12
                                                Fa0/13, Fa0/14, Fa0/15, Fa0/16
                                                Fa0/17, Fa0/18, Fa0/19, Fa0/20
                                                Fa0/21, Fa0/22, Fa0/23, Fa0/24
                                                Gig0/1, Gig0/2
10   VLAN0010                         active    
20   VLAN0020                         active    
1002 fddi-default                     active    
1003 token-ring-default               active    
1004 fddinet-default                  active    
1005 trnet-default                    active    
Switch(config)#interface f0/1
Switch(config-if)#switchport access vlan 10
Switch(config-if)#exit
Switch(config)#interface fa0/2
Switch(config-if)#switchport access vlan 20
Switch(config-if)#exit
Switch(config)#do show vlan brief

VLAN Name                             Status    Ports
---- -------------------------------- --------- -------------------------------
1    default                          active    Fa0/3, Fa0/4, Fa0/5, Fa0/6
                                                Fa0/7, Fa0/8, Fa0/9, Fa0/10
                                                Fa0/11, Fa0/12, Fa0/13, Fa0/14
                                                Fa0/15, Fa0/16, Fa0/17, Fa0/18
                                                Fa0/19, Fa0/20, Fa0/21, Fa0/22
                                                Fa0/23, Fa0/24, Gig0/1, Gig0/2
10   VLAN0010                         active    Fa0/1
20   VLAN0020                         active    Fa0/2
1002 fddi-default                     active    
1003 token-ring-default               active    
1004 fddinet-default                  active    
1005 trnet-default                    active   
#-------------------------Switch1是配置信息-------------------
#配置完成后，跨交换机相同vlan还无法访问，解决方法如下通过Trunk

Trunk

Trunk/中继链路/公共链路：允许所有vlan通过Trunk链路
通过在数据帧上添加标签，区分不同VLAN的数据

Trunk标签

• IEEE 802.1Q：公有协议，所有厂家支持，标签大小4个字节，属于内部标签
• ISL（Cisco私有），标签大小30字节(26+4)

交换机端口链路类型

接入端口：access端口，一般用于连接PC，只能属于某1个vlan，也只能传输1个vlan数据
中继端口，也称trunk端口，属于公共端口，允许所有vlan的数据通过。

配置trunk

#此实验连接上一个实验
#------------------配置Switch0上的fa0/4接口
Switch(config)#interface fa0/4
Switch(config-if)#switchport mode trunk

Switch(config-if)#
%LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/4, changed state to down

%LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/4, changed state to up
#------------------配置Switch1上的fa0/4接口
Switch(config)#interface fa0/4
Switch(config-if)#switchport mode trunk
Switch(config-if)#
Switch(config-if)#
Switch(config-if)#do show vlan brief

VLAN Name                             Status    Ports
---- -------------------------------- --------- -------------------------------
1    default                          active    Fa0/3, Fa0/5, Fa0/6, Fa0/7
                                                Fa0/8, Fa0/9, Fa0/10, Fa0/11
                                                Fa0/12, Fa0/13, Fa0/14, Fa0/15
                                                Fa0/16, Fa0/17, Fa0/18, Fa0/19
                                                Fa0/20, Fa0/21, Fa0/22, Fa0/23
                                                Fa0/24, Gig0/1, Gig0/2
10   VLAN0010                         active    Fa0/1
20   VLAN0020                         active    Fa0/2
1002 fddi-default                     active    
1003 token-ring-default               active    
1004 fddinet-default                  active    
1005 trnet-default                    active  
#--------------再次通过ping测试不同交换机上的同vlan之间通信

C:\\>ping 10.1.1.5

Pinging 10.1.1.5 with 32 bytes of data:

Reply from 10.1.1.5: bytes=32 time<1ms TTL=128
Reply from 10.1.1.5: bytes=32 time=4ms TTL=128

Ping statistics for 10.1.1.5:
    Packets: Sent = 2, Received = 2, Lost = 0 (0% loss),
Approximate round trip times in milli-seconds:
    Minimum = 0ms, Maximum = 4ms, Average = 2ms

Control-C
^C