Host-A
IP:192.168.56.129 OS:RHEL5.9 32bit Service: telnet-server
Host-B
IP:192.168.56.128 OS:RHEL5.9 32bit Service: telnet-client
在HostA上查看网卡信息
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# ifconfig eht0
eth0 Link encap:Ethernet HWaddr 00:0C:29:CC:30:9A
inet addr:192.168.56.129 Bcast:192.168.56.255 Mask:255.255.255.0
inet6 addr: fe80::20c:29ff:fecc:309a/64 Scope:Link
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:4914 errors:0 dropped:0 overruns:0 frame:0
TX packets:3705 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:2419811 (2.3 MiB) TX bytes:276508 (270.0 KiB)
Interrupt:67 Base address:0x2024
启动telnet服务
安装wireshark抓包工具
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#yum install -y wireshark
#yum install -y wireshark-gnome //把命令行工具和gnome图形工具的包一起安装上

开启wireshark抓包,为了方便分析包信息,写了过滤规则tcp.port == 23 and ip.dst == 192.168.56.129
在192.168.56.128机器上以root用户telnet登录192.168.56.129,首先查看网卡信息
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#ifconfig eth0
eth0 Link encap:Ethernet HWaddr 00:0C:29:E8:F9:FE
inet addr:192.168.56.128 Bcast:192.168.56.255 Mask:255.255.255.0
inet6 addr: fe80::20c:29ff:fee8:f9fe/64 Scope:Link
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:3518 errors:0 dropped:0 overruns:0 frame:0
TX packets:4232 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:276736 (270.2 KiB) TX bytes:2356751 (2.2 MiB)
Interrupt:67 Base address:0x2024
以root用户登录密码为redhat,成功登录!
在192.168.56.129用wireshark抓包
可以清楚的看到用户名为root密码为redhat,所以说telnet是一个明文传输的协议极其不安全,建议使用ssh v2版本。
以上我的实验就是为了证明telnet的明文传输密码,不经过任何加密措施,希望让大家有深刻的认识!
本文出自 “ 老徐的私房菜” 博客,谢绝转载!