SSH连接非常慢解决方法

2016-08-03    

 

现象

在局域网内，能ping通目标机器，并且时延是微秒级。

用ssh连局域网内其他linux机器，会等待10-30秒才有提示输入密码。严重影响工作效率。

原因

使用ssh –v，打开调试信息：

zhouhh@zhhofs:~$ ssh -v 192.168.12.16

on data /etc/ssh/ssh_config

debug1: Applying options for *

debug1: Connecting to 192.168.12.16 [192.168.12.16] port 22.

debug1: Connection established.

debug1: identity file /home/zhouhh/.ssh/identity type -1

debug1: identity file /home/zhouhh/.ssh/id_rsa type -1

debug1: identity file /home/zhouhh/.ssh/id_dsa type -1

debug1: Remote protocol version 2.0, remote software version OpenSSH_4.3

debug1: match: OpenSSH_4.3 pat OpenSSH_4*

debug1: Enabling compatibility mode for protocol 2.0

debug1: Local version string SSH-2.0-OpenSSH_5.1p1 Debian-6ubuntu2

debug1: SSH2_MSG_KEXINIT sent

debug1: SSH2_MSG_KEXINIT received

debug1: kex: server->client aes128-cbc hmac-md5 none

debug1: kex: client->server aes128-cbc hmac-md5 none

debug1: SSH2_MSG_KEX_DH_GEX_REQUEST(1024<1024<8192) sent

debug1: expecting SSH2_MSG_KEX_DH_GEX_GROUP

debug1: SSH2_MSG_KEX_DH_GEX_INIT sent

debug1: expecting SSH2_MSG_KEX_DH_GEX_REPLY

debug1: Host '192.168.12.16' is known and matches the RSA host key.

debug1: Found key in /home/zhouhh/.ssh/known_hosts:1

debug1: ssh_rsa_verify: signature correct

debug1: SSH2_MSG_NEWKEYS sent

debug1: expecting SSH2_MSG_NEWKEYS

debug1: SSH2_MSG_NEWKEYS received

debug1: SSH2_MSG_SERVICE_REQUEST sent

debug1: SSH2_MSG_SERVICE_ACCEPT received

debug1: Authentications that can continue: publickey,gssapi-with-mic,password

debug1: Next authentication method: gssapi-with-mic

debug1: An invalid name was supplied

Cannot determine realm for numeric host address

debug1: An invalid name was supplied

Cannot determine realm for numeric host address

debug1: An invalid name was supplied

debug1: Next authentication method: publickey

debug1: Trying private key: /home/zhouhh/.ssh/identity

debug1: Trying private key: /home/zhouhh/.ssh/id_rsa

debug1: Trying private key: /home/zhouhh/.ssh/id_dsa

debug1: Next authentication method: password

zhouhh@192.168.12.16's password:

debug1: Authentication succeeded (password).

debug1: channel 0: new [client-session]

debug1: Entering interactive session.

debug1: Sending environment.

debug1: Sending env LANG = zh_CN.UTF-8

Last login: Fri Dec 25 13:35:04 2009 from 192.168.11.146

可以看到如下的错误信息：

debug1: Next authentication method: gssapi-with-mic

debug1: An invalid name was supplied

Cannot determine realm for numeric host address

事实上，正是从gssapi-with-mic这一行开始，开始耗时间。

解决方法

1.修改本地机器的hosts文件，将目标机器的IP和域名加上去。或者让本机的DNS 服务器能解析目标地址。

vi /etc/hosts

2.修改本机的客户端配置文件ssh_conf，注意，不是sshd_conf

vi /etc/ssh/ssh_conf

找到 GSSAPIAuthentication yes

改为 GSSAPIAuthentication no

保存。