HP-UX Secure Shell Getting Started Guide HP-UX 11i v1, HP-UX 11i v2, and HP-UX 11i v3 (5900-3142, June 2013)

6 Enabling HP-UX Secure Shell to Take Advantage of High
Speed Networks
HP-UX Secure Shell includes a High Performance Enabled SSH/SCP (HPN) patch, which enables
HP-UX Secure Shell to take advantage of the large tcp send and receive buffers that are available
in high bandwidth networks.
In some situations (such as transfers on LANs), the HPN patch can degrade HP-UX Secure Shell
performance. In such cases, you can disable the HPN patch by setting HPNDisabled=no in the
sshd_config and ssh_config files. By default, the HPN patch is turned on.
Table 18 lists configuration directives that you can use to configure the HPN patch.
Table 18 Configuration Directives to Configure the HPN Patch
FunctionalityLocationConfiguration Directive
Use this configuration directive to set
the TCP socket receive buffer to n
Present on client and serverTcpRcvBuf=[int]KB
Kilobytes. You can set the buffer up to
the maximum socket size allowed by
the system. Use this configuration
directive in situations when the tcp
receive window is set low, but the
maximum buffer size is set higher. The
default value of this directive is the
current systemwide tcp receive buffer
size.
Use this configuration directive to
enable or disable the polling of the tcp
Present on client and serverTcpRcvBufPoll=[yes/no]
receive buffer while the connection is
active. The default value of this directive
is no.
Use this configuration directive to
enable or disable the use of the None
Present on client and serverNoneEnabled=[yes/no]
cipher. The default value of this
directive is no.
IMPORTANT: Enable this directive
with caution, because this allows users
to send unencrypted data through the
network. However, authentication
information remains encrypted.
Use this configuration directive to switch
the encryption cipher to the None
Present on clientNoneSwitch=[yes/no]
cipher after the user is authenticated.
You must enable NoneEnabled on the
client and server before enabling
NoneSwitch. The default value of this
directive is no.
NOTE: You cannot use the None
cipher in interactive Shell sessions. If
you do so, HP-UX Secure Shell fails
without displaying any error messages.
Use this configuration directive to
disable the HPN functionality. You can
Present on client and serverHPNDisabled=[yes/no]
disable HPN if the impact of the HPN
code produces a net decrease in
performance. This can happen
sometimes when there are transfers on
53