3COM用一种很希奇的方式来维护他们售出的设备，那就是后门密码，任何的下列密码都是最高权限，可以自由设置设备。
　　
　　 CoreBuilder 6000/2500 - username: debug passWord: synnet
　　 CoreBuilder 3500 (Version 1.0) - username: debug password: synnet
　　 CoreBuilder 7000 - username: tech password: tech
　　 SuperStack II Switch 2200 - username: debug password: synnet
　　 SuperStack II Switch 2700 - username: tech password: tech
　　 Bay Networks似乎感觉3com的这种方式很好，于是在他们350（也许还有其他型号）的产品里也加进了后门密码 "NetICs" ，类似情况没有在accelar产品系列里获得报道。
　　
　　 除了交换机之外，3com在访问服务器里也加入了默认密码，用户名是"adm"，密码为空。
　　
　　 在极端的情况下，这可以作为恢复密码的一个手段。
　　
　　 叉开一些话题，我在使用Nortel(Bay)的交换机时，不小心发现几乎Bay全部产品都有隐藏模式， 350/450上是按一下 ctrl-H 或者是退格键，可以进入Hidden Menu。
　　 在Accelar 1100/1200 上，输入 sh h ，你会看到一些隐藏命令的列表，其中有个
　　 privilige命令，必须有rwa的用户登录以后执行，执行以后，可以进入一个特权模式，
　　 提示符也变为 * ，然后可以输入"shell"，进入一个非凡的环境，看help，是些调试功能，
　　 呵呵，很有趣，希望有人能够继续挖掘下去。http://go1.163.com/~watchsea/otherswi.htm
　　3Com Security Advisory for CoreBuilder and SuperStack II customers
　　 3Com is issuing a security advisory affecting select CoreBuilder LAN switches and SuperStack II Switch prodUCts. This is in response to the widespread distribution of special logins intended for service and recovery procedures issued only by 3Com''s Customer Service Organization under conditions of extreme emergency, such as in the event of a customer losing passwords.
　　
　　 Due to this disclosure some 3Com switching products may be vulnerable to security breaches caused by unauthorized Access via special logins.
　　
　　 To address these issues, customers should immediately log in to their switches via the following usernames and passwords. They should then proceed to change the password via the appropriate Password parameter to prevent unauthorized access.
　　
　　
　　 CoreBuilder 6000/2500 - username: debug password: synnet
　　 CoreBuilder 3500 (Version 1.0) - username: debug password: synnet
　　 CoreBuilder 7000 - username: tech password: tech
　　 SuperStack II Switch 2200 - username: debug password: synnet
　　 SuperStack II Switch 2700 - username: tech password: tech
　　 The CoreBuilder 3500 (Version 1.1), SuperStack II Switch 3900 and 9300 also have these mechanisms, but the special login password is changed to match the admin level password when the admin level password is changed.
　　
　　 Customers should also immediately change the SNMP Community string from the default to a proprietary and confidential identifier known only to authorized network management staff. This is due to the fact that the admin password is available through a specific proprietary MIB variable when accessed through the read/write SNMP community string.
　　
　　 This issue applies only to the CoreBuilder 2500/6000/3500 and SuperStack II Switch 2200/3900/9300.
　　
　　 Fixed versions of software for CoreBuilder 2500/6000/3500 and SuperStack II Switch 2200/3900/9300 are available below.
　　
　　 General administration of these systems should still be performed through the normal documented usernames and passwords. Other facilities found under these special logins are for diagnostic purposes and should only be used under specific guidance from 3Com''s Customer Service Organization.