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
本文出自 “考拉先生” 博客，请务必保留此出处http://koala003.blog.51cto.com/9996246/1689914
解决linux ssh客户端SSH连接linux服务器很慢的问题
原文地址：http://koala003.blog.51cto.com/9996246/1689914
