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Week 5.md

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第五週筆記

第一個實驗 -- 將主機配置為路由器

拓樸架構

h1 <-> h2 <-> h3（h2 將被配置為路由器）

程式碼

#!/usr/bin/env python
from mininet.cli import CLI
from mininet.net import Mininet
from mininet.link import Link,TCLink,Intf

if '__main__' == __name__:
  net = Mininet(link=TCLink)
  h1 = net.addHost('h1')
  h2 = net.addHost('h2')
  h3 = net.addHost('h3')
  Link(h1, h2)
  Link(h2, h3, intfName1='h2-eth1')
  net.build()
  h2.cmd('ifconfig h2-eth0 192.168.10.1 netmask 255.255.255.0')
  h2.cmd('ifconfig h2-eth1 192.168.20.1 netmask 255.255.255.0')
  h2.cmd("echo 1 > /proc/sys/net/ipv4/ip_forward")
  h1.cmd("ifconfig h1-eth0 0")
  h3.cmd("ifconfig h3-eth0 0")
  h1.cmd("ip address add 192.168.10.2/24 dev h1-eth0")
  h1.cmd("ip route add default via 192.168.10.1 dev h1-eth0")
  h3.cmd("ip address add 192.168.20.2/24 dev h3-eth0")
  h3.cmd("ip route add default via 192.168.20.1 dev h3-eth0")
  CLI(net)
  net.stop()

執行結果


第二個實驗 -- 啟動 DHCP 伺服器

拓樸架構

h1 <-> h2 <-> h3（h2 將被配置為路由器。另外，DHCP 伺服器在 h2 上運行）

程式碼

  • 實驗之前，請使用 sudo apt-get install isc-dhcp-server 指令在 Ubuntu 中安裝 DHCP 伺服器
#!/usr/bin/env python
from mininet.cli import CLI
from mininet.net import Mininet
from mininet.link import Link,TCLink,Intf
 
if '__main__' == __name__:
  net = Mininet(link=TCLink)
  h1 = net.addHost('h1')
  h2 = net.addHost('h2')
  h3 = net.addHost('h3')
  Link(h1, h2, intfName1='h1-eth0', intfName2='h2-eth0')
  Link(h2, h3, intfName1='h2-eth1', intfName2='h3-eth0')
  net.build()
  h2.cmd('ifconfig h2-eth0 192.168.10.1 netmask 255.255.255.0')
  h2.cmd('ifconfig h2-eth1 192.168.20.1 netmask 255.255.255.0')
  h2.cmd("echo 1 > /proc/sys/net/ipv4/ip_forward")
  h2.cmd("service isc-dhcp-server restart &")
  h1.cmd("ifconfig h1-eth0 0")
  h3.cmd("ifconfig h3-eth0 0")
  h1.cmd("dhclient h1-eth0")
  h3.cmd("dhclient h3-eth0")
  CLI(net)
  net.stop()
  • 在運行 mininet 腳本之前，我們必須配置 DHCP 伺服器。在 /etc/dhcp 下編輯 dhcpd.conf：gedit /etc/dhcp/dhcpd.conf &，編譯內容如下
#!/usr/bin/env python
from mininet.cli import CLI
from mininet.net import Mininet
from mininet.link import Link,TCLink,Intf

if '__main__' == __name__:
  net = Mininet(link=TCLink)
  h1 = net.addHost('h1')
  h2 = net.addHost('h2')
  h3 = net.addHost('h3')
  Link(h1, h2, intfName1='h1-eth0', intfName2='h2-eth0')
  Link(h2, h3, intfName1='h2-eth1', intfName2='h3-eth0')
  net.build()
  h2.cmd('ifconfig h2-eth0 192.168.10.1 netmask 255.255.255.0')
  h2.cmd('ifconfig h2-eth1 192.168.20.1 netmask 255.255.255.0')
  h2.cmd("echo 1 > /proc/sys/net/ipv4/ip_forward")
  h2.cmd("service isc-dhcp-server restart &")
  h1.cmd("ifconfig h1-eth0 0")
  h3.cmd("ifconfig h3-eth0 0")
  h1.cmd("dhclient h1-eth0")
  h3.cmd("dhclient h3-eth0")
  CLI(net)
  net.stop()

執行結果

第三個實驗 -- 在 h2 添加 NAT 功能

拓樸架構

h1 <-> h2 <-> h3（h2 將被配置為路由器。此外，使用 iptables 使 h2 具有 NAT 功能）

程式碼

#!/usr/bin/env python
from mininet.cli import CLI
from mininet.net import Mininet
from mininet.link import Link,TCLink,Intf

if '__main__' == __name__:
  net = Mininet(link=TCLink)
  h1 = net.addHost('h1')
  h2 = net.addHost('h2')
  h3 = net.addHost('h3')
  Link(h1, h2, intfName1='h1-eth0', intfName2='h2-eth0')
  Link(h2, h3, intfName1='h2-eth1', intfName2='h3-eth0')
  net.build()
  h2.cmd('ifconfig h2-eth0 192.168.10.1 netmask 255.255.255.0')
  h2.cmd('ifconfig h2-eth1 192.168.20.1 netmask 255.255.255.0')
  h2.cmd("echo 1 > /proc/sys/net/ipv4/ip_forward")
  h2.cmd("iptables -t nat -A POSTROUTING -o h2-eth1 -s 192.168.10.0/24 -j MASQUERADE")
  h2.cmd("service isc-dhcp-server restart &")
  h1.cmd("ifconfig h1-eth0 0")
  h3.cmd("ifconfig h3-eth0 0")
  h1.cmd("dhclient h1-eth0")
  h3.cmd("dhclient h3-eth0")
  CLI(net)
  net.stop()

執行結果

延伸學習

  1. Mininet Operations