在Catalyst 中控制对Telnet的访问
Test_1(config)#access-list 2 permit 172.16.0.0 0.0.255.255 （定义标准的访问列表）
Test_1(config)#line vty 0 15（进入telnet端口，最多允许16个telnet的会话）
Test_1(config-line)#access-class 2 in（应用上述定义的访问列表，即只有172.16.0.0/16的网段可以实现对交换机的telnet会话

设置交换机的enable 密码
Test_1(config)#enable password test
Test_1(config)#enable secret test
The enable secret you have chosen is the same as your enable password.
This is not recommended. Re-enter the enable secret.
注：对于如上的密码，secret的优先级更高，优先起作用。

设置console口密码
Test_1(config)#line con 0
Test_1(config-line)#password test
Test_1(config-line)#

设置对telnet的密码：
Test_1(config)#line vty 0 15
Test_1(config-line)#login
Test_1(config-line)#password test
Test_1(config-line)#

设置登陆用户名和密码：

Test_1(config)#username test password test
Test_1(config)#

Test_1#show running

Current configuration:
!
version 12.0
no service pad
service timestamps debug uptime
service timestamps log uptime
no service password-encryption
!
hostname Test_1

enable secret 5 $1$dddddb1mb$p6XgV/PY9WqvJy9MrHZFG/
enable password test
!
username test password 0 test
!
ip subnet-zero
!
interface FastEthernet0/1
!
interface FastEthernet0/2
!
interface FastEthernet0/3
!
interface FastEthernet0/4
!
interface FastEthernet0/5
!
interface FastEthernet0/6
!
interface FastEthernet0/24
!
interface GigabitEthernet0/1
!
interface GigabitEthernet0/2
!
interface VLAN1
ip address 172.16.1.3 255.255.0.0
no ip directed-broadcast
no ip route-cache
!
access-list 2 permit 172.16.0.0 0.0.255.255
!
line con 0
password test
transport input none
stopbits 1
line vty 0 4
access-class 2 in
password test
login
line vty 5 15
access-class 2 in
password test

login
!
end
Test_1#