linux下SSH遠程鏈接服務慢解決方案

一、適用命令及方案以下：
【遠程鏈接及執行命令】
ssh -p22 root@10.0.0.19
ssh -p22 root@10.0.0.19 /sbin/ifconfig
【遠程拷貝：推送及拉取】
scp -P22 -r -p /etc root@10.0.0.19:/tmp/
scp -P22 -r -p root@10.0.0.19:/tmp/ /etc
【安全的FTP功能】
sftp -oPort=22 root@10.0.0.19
【無密碼驗證方案】
例如利用sshkey批量分發文件，執行部署操做。

二、鏈接慢的主要緣由是DNS解析致使
解決方法：

一、在ssh服務端上更改/etc/ssh/sshd_config文件中的配置爲以下內容：
UseDNS no
# GSSAPI options
GSSAPIAuthentication no
而後，執行/etc/init.d/sshd restart重啓sshd進程使上述配置生效，在鏈接通常就不慢了。

二、若是還慢的話，檢查ssh服務端上/etc/hosts文件中，127.0.0.1對應的主機名是否和
uname -n的結果同樣，或者把本機ip和hostname(uname -n結果)加入到/etc/hosts裏。

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[root @C64  ~] # uname -n C64 [root @C64  ~] # cat /etc/hosts #modi by oldboy 11:12 2013/9/24 127.0.0.1   C64 localhost localhost.localdomain localhost4 localhost4.localdomain4 ::1         localhost localhost.localdomain localhost6 localhost6.localdomain6 10.0.0.18   C64 ################

三、利用ssh-v的調試功能查找慢的緣由
其實能夠用下面的命令調試爲何慢的細節（學習這個思路很重要）。

 

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[root @C64  ~] # ssh -v root@10.0.0.19 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 10.0.0.19 [10.0.0.19] port 22. debug1: Connection established. debug1: permanently_set_uid: 0/0 debug1: identity file /root/.ssh/identity type -1 debug1: identity file /root/.ssh/id_rsa type -1 debug1: identity file /root/.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_5.3 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 The authenticity of host  '10.0.0.19 (10.0.0.19)'  can 't be established. RSA key fingerprint is ca:18:42:76:0e:5a:1c:7d:ef:fc:24:75:80:11:ad:f9. Are you sure you want to continue connecting (yes/no)? yes =======>老男孩老師評：這裏就是提示保存密鑰的交互提示。 Warning: Permanently added ' 10.0.0.19 ' (RSA) to the list of known hosts. 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,password debug1: Next authentication method: publickey debug1: Trying private key: /root/.ssh/identity debug1: Trying private key: /root/.ssh/id_rsa debug1: Trying private key: /root/.ssh/id_dsa debug1: Next authentication method: password root@10.0.0.19' s password: =======>老男孩老師評：這裏就是提示輸入密碼的交互提示。 debug1: Authentication succeeded (password). debug1: channel 0: new [client-session] debug1: Entering interactive session. debug1: Sending environment. debug1: Sending env LANG = en_US.UTF-8 Last login: Tue Sep 24 10:30:02 2013 from 10.0.0.18 在遠程鏈接時若是慢就能夠肯定卡在哪了。 [root @C64_A  ~] # ssh -v oldboy@10.0.0.17 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 10.0.0.17 [10.0.0.17] port 22. debug1: Connection established. debug1: permanently_set_uid: 0/0 debug1: identity file /root/.ssh/identity type -1 debug1: identity file /root/.ssh/id_rsa type -1 debug1: identity file /root/.ssh/id_dsa type 2 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  '10.0.0.17'  is known and matches the RSA host key. debug1: Found key  in  /root/.ssh/known_hosts:2 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

上述配置沒配就發現卡到gssapi這。就大概知道是gssapi的問題。
實際上在linux系統優化部分就應該優化SSH服務的此處。