linux下SSH远程连接服务慢解决方案

秒速五厘米 2022-07-14 05:54 435阅读 0赞

1、适用命令及方案如下：  
【远程连接及执行命令】  
ssh -p22 root@10.0.0.19  
ssh -p22 root@10.0.0.19 /sbin/ifconfig  
【远程拷贝：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  
【无密码验证方案】  
例如利用sshkey批量分发文件，执行部署操作。

2、连接慢的主要原因是DNS解析导致  
解决方法：

1、在ssh服务端上更改/etc/ssh/sshd\_config文件中的配置为如下内容：

UseDNS no
    # GSSAPI options
    GSSAPIAuthentication no
    然后，执行/etc/init.d/sshd restart重启sshd进程使上述配置生效，在连接一般就不慢了。
    
    2、如果还慢的话，检查ssh服务端上/etc/hosts文件中，127.0.0.1对应的主机名是否和
    uname -n的结果一样，或者把本机ip和hostname(uname -n结果)加入到/etc/hosts里。
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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
    ################
    
    3、利用ssh-v的调试功能查找慢的原因
    其实可以用下面的命令调试为什么慢的细节（学习这个思路很重要）。
    [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 =======>这里就是提示保存密钥的交互提示。 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:
    =======>这里就是提示输入密码的交互提示。
    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
    在远程连接时如果慢就可以确定卡在哪了。
    [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

上述配置没配就发现卡到gssapi这。就大概知道是gssapi的问题。  
实际上在linux系统优化部分就应该优化SSH服务的此处。