linux下ssh服务器很慢怎么办

在linux上使用ssh客户端连接另一台的linux服务器时，出现了连接慢的情况。但是换一台客户端去连发现速度正常。推测ssh客户端出现为问题。

于是使用使用ssh -v  IP 调试，果然发现问题。输出如下：

[root@jump1 ~]# ssh -v 10.60.9.32

OpenSSH_5.3p1, OpenSSL 1.0.1e-fips 11 Feb 2013

debug1: Reading configuration data /etc/ssh/ssh_config

debug1: Applying options for *

debug1: Connecting to 10.60.9.32 [10.60.9.32] port 22.

debug1: Connection established.

debug1: permanently_set_uid: 0/0

debug1: identity file /root/.ssh/identity type -1

debug1: identity file /root/.ssh/identity-cert type -1

debug1: identity file /root/.ssh/id_rsa type -1

debug1: identity file /root/.ssh/id_rsa-cert type -1

debug1: identity file /root/.ssh/id_dsa type -1

debug1: identity file /root/.ssh/id_dsa-cert type -1

debug1: identity file /root/.ssh/id_ecdsa type -1

debug1: identity file /root/.ssh/id_ecdsa-cert 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_5.3

debug1: SSH2_MSG_KEXINIT sent

debug1: SSH2_MSG_KEXINIT received

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

debug1: kex: client->server aes128-ctr 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 '10.60.9.32' is known and matches the RSA host key.

debug1: Found key in /root/.ssh/known_hosts:9

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

可在最后一条，应该和“ gssapi-with-mic”有关，经过排查，终于发现问题，果然是ssh客户端文件有问题。是ssh客户端连接时会进行反向查询所致。

修改方法如下：

修改本机的客户端配置文件ssh_config，注意，不是ssh_config

vi /etc/ssh/ssh_config

找到 

GSSAPIAuthentication yes 

改为 

GSSAPIAuthentication no 

再去试一下，速度正常了

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