METRODATA NetTESTER FAMILY USER MANUAL
76-02-107 Rev.A
Page 36 of 133
Note
: Modern web browsers tend to open several TCP connections at once for a
single session, so the connection limit is likely to be reached sooner than expected
when using HTTP access.
7.5 Telnet and SSH
Telnet [3] and SSHv2 [4] are both protocols offering terminal-like access to the unit
over a network connection. The primary difference is that SSH offers a secure
connection, whereas Telnet does not. Either or both may be enabled as methods of
accessing the unit. If security is a consideration, however, it is recommended that
SSH is enabled and Telnet disabled.
Up to 8 concurrent sessions are supported (Telnet, SSH or a mix).
The SSHv2 server has been verified with several of the more popular SSH clients
including:
•
PuTTY
•
Tera Term TTSSH
•
BitVise SSH Client
SSH also provides the transport and authentication for SFTP (see section 7.8).
7.5.1 SSH Connection Delays
When connecting via SSH there is typically a delay of several seconds whilst initial
cryptographic functions are performed. Once this is done, the user interface
operates as normal. This delay can be shortened by setting the SSH client to select
the Diffie-Hellman group 1 key exchange algorithm in preference to Diffie-Hellman
group 14. This does, however, reduce the level of security, and so should be used
with caution.
7.6 HTTP/Web
The unit supports a basic web server that presents a browser-accessible version of
the user interface (see section 13.2).
Secure (HTTPS) access is not supported, and it is recommended that HTTP access
is disabled for security-conscious applications.
7.7 SNMP
Simple Network Management Protocol (SNMP) [5] can be viewed as an alternate
means of managing the unit, presenting a completely different interface to the menu-
driven user interface used across the other management access methods (terminal,
Telnet, SSH and HTTP).
Manageable items are defined as abstract objects in Management Information Base
(MIB) documents. These are used by an SNMP manager to guide access to the
objects made available by the SNMP agent within the unit.
