核心：
服务器端sshd配置文件 /etc/ssh/sshd_config 看是否有如下的两条配置条目
GSSAPIAuthentication no UseDNS no
如果前面带#，请把#删掉，或者新添加入这样两行。
然后重启sshd服务，或者重启服务器也可以。
注意是文件 /etc/ssh/sshd_config 而不是/etc/ssh/ssh_config
ssh 登录远程服务器，速度非常慢，通过网上查询，发现有一个参数 -v 可以输出显示连接的具体消息。于是连接加上这个参数连接
[feng@fsc ~]$ ssh -v foo.path8.net OpenSSH_5.3p1, OpenSSL 1.0.0-fips 29 Mar 2010 debug1: Reading configuration data /etc/ssh/ssh_config debug1: Applying options for * debug1: Connecting to v.path8.net [64.120.xxx.xxx] port 22. debug1: Connection established. debug1: identity file /home/feng/.ssh/identity type -1 debug1: identity file /home/feng/.ssh/id_rsa type 1 debug1: identity file /home/feng/.ssh/id_dsa type -1 debug1: Remote protocol version 2.0, remote software version OpenSSH_5.3 debug1: match: OpenSSH_5.3 pat OpenSSH* 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 'v.path8.net' is known and matches the RSA host key. debug1: Found key in /home/feng/.ssh/known_hosts:4 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-keyex,gssapi-with-mic,password debug1: Next authentication method: gssapi-keyex debug1: No valid Key exchange context debug1: Next authentication method: gssapi-with-mic /*--------- 这里停留的十多秒钟时间 ----------*/ reverse mapping checking getaddrinfo for srv3.mktmaster.net [64.120.xxx.xxx] failed - POSSIBLE BREAK-IN ATTEMPT! debug1: Unspecified GSS failure. Minor code may provide more information Credentials cache file '/tmp/krb5cc_501' not found debug1: Unspecified GSS failure. Minor code may provide more information Credentials cache file '/tmp/krb5cc_501' not found debug1: Unspecified GSS failure. Minor code may provide more information debug1: Next authentication method: publickey debug1: Offering public key: /home/feng/.ssh/id_rsa debug1: Server accepts key: pkalg ssh-rsa blen 277 debug1: Authentication succeeded (publickey). debug1: channel 0: new [client-session] debug1: Requesting no-more-sessions@openssh.com debug1: Entering interactive session. debug1: Sending environment. debug1: Sending env XMODIFIERS = @im=ibus debug1: Sending env LANG = zh_CN.utf8 Last login: Mon Oct 24 10:26:30 2011 from 124.79.xxx.xxx [feng@v ~]$
大概就是GSSAPIAuthentication这个参数的问题了，之前就是因为连接速度慢，网上查，说是/etc/ssh/sshd_config 里加入参数 UseDNS no，再加个GSSAPIAuthentication yes, 结果速度还是慢。
于是去把这行改为GSSAPIAuthentication no，重启服务器端的ssdh服务，再次连接，速度快多了。
参考