3Com Switch 4800G 24-Port Configuration Manual page 1122

1122 C 88: SSH C
HAPTER ONFIGURATION
Run PuTTYGen.exe, choose SSH2-(RSA) and click Generate.
Figure 334 Generate a client key pair (1)
While generating the key pair, you must move the mouse continuously and keep
the mouse off the green process bar shown in Figure 335. Otherwise, the process
bar stops moving and the key pair generating process is stopped.