APC AP9312TH 用户手册

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Environmental Monitoring Unit: User’s Guide
26
Security
Authentication
Authentication 
versus encryption
The Environmental Monitoring Unit controls access by providing basic 
authentication through user names, passwords, and 
IP
 addresses, but 
provides no type of encryption. These basic security features are 
sufficient for most environments, in which sensitive data is not being 
transferred. To ensure that data and communication between the 
Environmental Monitoring Unit and the client interfaces, such as Telnet 
and the Web browser, cannot be captured, you can provide a greater 
level of security by enabling 
MD5
 authentication for the Web interface. 
See 
.
MD5 
authentication 
(Web interface)
The Web interface option for 
MD5
 authentication enables a higher level 
of access security than the basic 
HTTP
 authentication scheme. The 
MD5
 scheme is similar to 
CHAP
 and 
PAP
 remote access protocols. 
Enabling 
MD5
 implements the following security features:
The Web server requests a user name and a password phrase 
(distinct from the password). The user name and password 
phrase are not transmitted over the network, as they are in 
basic authentication. Instead, a Java login applet combines the 
user name, password phrase, and a unique session challenge 
number to calculate an 
MD5
 hash number. Only the hash 
number is returned to the server to verify that the user has the 
correct login information; 
MD5
 authentication does not reveal 
the login information. 
In addition to the login authentication, each form post for 
configuration or control operations is authenticated with a 
unique challenge and hash response.
After the authentication login, subsequent page access is 
restricted by 
IP
 addresses and a hidden session cookie. (You 
must have cookies enabled in your browser.) Pages are 
transmitted in their plain-text form, with no encryption.
If you use 
MD5
 authentication, which is available only for the Web 
interface, disable the less secure interfaces, including Telnet, 
FTP
, and 
SNMP
. For 
SNMP
, you can disable write-only access so that read 
access and trap facilities are still available. For additional information on 
MD5
 authentication, see 
RFC
 document #
1321
 at the Web site of the 
Internet Engineering Task Force. For 
CHAP
, see 
RFC
 document #
1994
.
Firewalls
Although 
MD5
 authentication provides a much higher level of security 
than the plain-text access methods, complete protection from security 
breaches is almost impossible to achieve. Well-configured firewalls are 
an essential element in an overall security scheme.
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