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linux下SSH遠程連接服務慢解決方案

1、適用命令及方案如下:

【遠程連接及執行命令】

ssh -p22 [email protected]

ssh -p22 [email protected] /sbin/ifconfig

【遠程拷貝:推送及拉取】

scp -P22 -r -p /etc [email protected]:/tmp/

scp -P22 -r -p [email protected]:/tmp/ /etc

【安全的FTP功能】

sftp -oPort=22 [email protected]

【無密碼驗證方案】

例如利用sshkey批量分發文件,執行部署操作。

2、連接慢的主要原因是DNS解析導致

解決方法:

1、在ssh服務端上更改/etc/ssh/sshd_config文件中的配置為如下內容:

UseDNS no

# GSSAPI options

GSSAPIAuthentication no

然後,執行/etc/init.d/sshd restart重啟sshd進程使上述配置生效,在連接一般就不慢了。

 

2、如果還慢的話,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的結果一樣,或者把本機ip和hostname(uname -n結果)加入到/etc/hosts裡。

[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
################

3、利用ssh-v的調試功能查找慢的原因

其實可以用下面的命令調試為什麼慢的細節(學習這個思路很重要)。

[root@C64 ~]# ssh -v [email protected]
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:這裡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
[email protected]'s password:
=======>老男孩老師評:這裡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
在遠程連接時如果慢就可以確定卡在哪了。
[root@C64_A ~]# ssh -v [email protected]
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。

本文出自 “老男孩linux運維” 博客,請務必保留此出處http://oldboy.blog.51cto.com/2561410/1300964

 

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