我有一个非常有趣的情况。 我有一台运行CentOS5.5的服务器，每当我尝试使用任何外部接口的ssh时，都会持续4秒以上的延迟。 每当我使用内部接口时都没有这种延迟。 例如，从mycomputer2进入mycomputer1的时间不长，但是从mycomputer2进入mycomputer1.com进入发生延迟的外部接口。 / var / log / messages在使用密码login时显示了这一点，有一些redactions：
Mar 18 10:18:06 somecomputer sshd[788]: pam_unix(sshd:auth): authentication failure; Mar 18 10:18:06 somecomputer sshd[788]: pam_krb5[788]: TGT verified using key for ... Mar 18 10:18:06 somecomputer sshd[788]: pam_krb5[788]: authentication succeeds for user Mar 18 10:18:12 somecomputer sshd[788]: Accepted password for user from computer port myport ssh2 Mar 18 10:18:13 somecomputer sshd[788]: pam_unix(sshd:session): session opened for user myuser by (uid=0) 这是/etc/pam.d/sshd：
auth include system-auth account required pam_nologin.so account include system-auth password include system-auth session optional pam_keyinit.so force revoke session include system-auth session required pam_loginuid.so session required pam_limits.so
这是system-auth：
auth required pam_env.so auth sufficient pam_unix.so likeauth nullok auth sufficient pam_krb5.so use_first_pass auth required pam_deny.so account required pam_unix.so broken_shadow account sufficient pam_succeed_if.so uid < 100 quiet account [default=bad success=ok user_unknown=ignore] pam_krb5.so account required pam_permit.so password requisite pam_cracklib.so retry=3 password sufficient pam_krb5.so use_authtok password sufficient pam_unix.so nullok use_authtok md5 shadow password required pam_deny.so session required pam_limits.so session required pam_unix.so session required pam_krb5.so use_first_pass
这是一个DNS问题，将UseDNS no添加到/ etc / ssh / sshd_config中，重新加载ssh并查看是否有更改。