Xshell连接Oracle Linux 7.5校验慢的问题

环境

Xshell 6
Oracle Linux 7.5

问题

Xshell连Oracle Linux 7.5，连接阶段非常慢，但之前使用Oracle Linux 5.5一切正常。

解决

问题原因

根据多方查找，发现问题是Xshell在通过ssh连接Oracle Linux 7.5时会校验DNS所致。

问题解决

关闭DNS校验

1	[oracle@ora122 ~]$ vi /etc/ssh/sshd_config

文件中查找UsePAM yes，在其后面添加UseDNS no，如下：

#GSSAPIKeyExchange no
#GSSAPIEnablek5users no

# Set this to 'yes' to enable PAM authentication, account processing,
# and session processing. If this is enabled, PAM authentication will
# be allowed through the ChallengeResponseAuthentication and
# PasswordAuthentication.  Depending on your PAM configuration,
# PAM authentication via ChallengeResponseAuthentication may bypass
# the setting of "PermitRootLogin without-password".
# If you just want the PAM account and session checks to run without
# PAM authentication, then enable this but set PasswordAuthentication
# and ChallengeResponseAuthentication to 'no'.
# WARNING: 'UsePAM no' is not supported in Red Hat Enterprise Linux and may cause several
# problems.
UsePAM yes
UseDNS no

#AllowAgentForwarding yes
#AllowTcpForwarding yes

重启ssh服务，问题解决。

1	systemctl restart sshd