ssh与sftp登录对端缓慢问题

SSH is slow to make a connection

1. su

2. vi /etc/ssh/sshd_config

3. add UseDNS no

4. /etc/init.d/sshd restart

 ​使用strace命令来跟踪慢的问题

• 
  
• 检查服务器SSH配置文件（sshd_config）的UseDNS配置项是否开启
• 
  

vi /etc/ssh/sshd_config

• 
  
•  该配置文件，默认会有一个注释的（#UseDNS yes）配置项，但该项的缺省值是yes，所以需要显式地设置为no
• 
  

1. 
   
2.  
   
   #UseDNS yes
3.  
   
   UseDNS no
4. 
   

 注：UseDNS配置项主要用于安全加固，默认为yes开启时，连接过程慢是因为客户端（Client）通过SSH协议连接服务端（Server）时，服务端会进行4次的DNS反向解析请求（每次请求失败间隔5s），即服务端会根据客户端的IP进行DNS反向解析查询出客户端的主机名，然后再根据查询出的主机名进行DNS正向解析，最后验证解析出来的IP与原始客户端IP是否一致，已达到防止客户端欺骗的目的。如果我们的客户端IP在DNS服务器中没有配置PTR反向解析记录，那么就会导致请求无响应，直至请求超时才会进行下一步的SSH连接。

• 
  
• 重启ssh服务 
• 
  

service sshd restart

vscode sftp插件问题：

​​​​https://github.com/liximomo/vscode-sftp/wiki/Common-Config​​

 

更改connectTimeout的值即可完成最大超时时间的配置，改成300，

默认值是：

connectTimeout

number - the maximum connection time

Default

10000

 

SFTP点上传有时候没有反应，我们观察下正常的上传日志：

run command 'Upload File'

[03-09 00:59:15] [warn] ENOENT: no such file or directory, open 'C:\Users\Admin\.ssh\config' load C:\Users\Admin\.ssh\config failed

[03-09 00:59:15] [trace] handle upload file for e:xxx.js

[03-09 00:59:15] [debug] Local ident: 'SSH-2.0-ssh2js0.4.5'

[03-09 00:59:15] [debug] Client: Trying 7.13.18.230 on port 19800 ...

[03-09 00:59:15] [debug] Client: Connected

[03-09 00:59:15] [debug] Remote ident: 'SSH-2.0-OpenSSH_7.4'

[03-09 00:59:15] [debug] Outgoing: Writing KEXINIT

[03-09 00:59:15] [debug] DEBUG: Comparing KEXINITs ...

[03-09 00:59:15] [debug] (local) KEX algorithms: ecdh-sha2-nistp256,ecdh-sha2-nistp384,ecdh-sha2-nistp521,diffie-hellman-group-exchange-sha256,diffie-hellman-group14-sha1

[03-09 00:59:15] [debug] (remote) KEX algorithms: curve25519-sha256,[e-mail],ecdh-sha2-nistp256,ecdh-sha2-nistp384,ecdh-sha2-nistp521,diffie-hellman-group-exchange-sha256,diffie-hellman-group16-sha512,diffie-hellman-group18-sha512,diffie-hellman-group-exchange-sha1,diffie-hellman-group14-sha256,diffie-hellman-group14-sha1,diffie-hellman-group1-sha1

[03-09 00:59:15] [debug] KEX algorithm: ecdh-sha2-nistp256

[03-09 00:59:15] [debug] (local) Host key formats: ssh-ed25519,ssh-rsa,ecdsa-sha2-nistp256,ecdsa-sha2-nistp384,ecdsa-sha2-nistp521

[03-09 00:59:15] [debug] (remote) Host key formats: ssh-rsa,rsa-sha2-512,rsa-sha2-256,ecdsa-sha2-nistp256,ssh-ed25519

[03-09 00:59:15] [debug] Host key format: ssh-ed25519

[03-09 00:59:15] [debug] (local) Client->Server ciphers: aes128-ctr,aes192-ctr,aes256-ctr,aes128-gcm,[e-mail],aes256-gcm,[e-mail]

[03-09 00:59:15] [debug] (remote) Client->Server ciphers: [e-mail],aes128-ctr,aes192-ctr,aes256-ctr,[e-mail],[e-mail],aes128-cbc,aes192-cbc,aes256-cbc,blowfish-cbc,cast128-cbc,3des-cbc

[03-09 00:59:15] [debug] Client->Server Cipher: aes128-ctr

[03-09 00:59:15] [debug] (local) Server->Client ciphers: aes128-ctr,aes192-ctr,aes256-ctr,aes128-gcm,[e-mail],aes256-gcm,[e-mail]

[03-09 00:59:15] [debug] (remote) Server->Client ciphers: [e-mail],aes128-ctr,aes192-ctr,aes256-ctr,[e-mail],[e-mail],aes128-cbc,aes192-cbc,aes256-cbc,blowfish-cbc,cast128-cbc,3des-cbc

[03-09 00:59:15] [debug] Server->Client Cipher: aes128-ctr

[03-09 00:59:15] [debug] (local) Client->Server HMAC algorithms: hmac-sha2-256,hmac-sha2-512,hmac-sha1

[03-09 00:59:15] [debug] (remote) Client->Server HMAC algorithms: [e-mail],[e-mail],[e-mail],[e-mail],[e-mail],[e-mail],[e-mail],hmac-sha2-256,hmac-sha2-512,hmac-sha1

[03-09 00:59:15] [debug] Client->Server HMAC algorithm: hmac-sha2-256

[03-09 00:59:15] [debug] (local) Server->Client HMAC algorithms: hmac-sha2-256,hmac-sha2-512,hmac-sha1

[03-09 00:59:15] [debug] (remote) Server->Client HMAC algorithms: [e-mail],[e-mail],[e-mail],[e-mail],[e-mail],[e-mail],[e-mail],hmac-sha2-256,hmac-sha2-512,hmac-sha1

[03-09 00:59:15] [debug] Server->Client HMAC algorithm: hmac-sha2-256

[03-09 00:59:15] [debug] (local) Client->Server compression algorithms: none,[e-mail],zlib

[03-09 00:59:15] [debug] (remote) Client->Server compression algorithms: none,[e-mail]

[03-09 00:59:15] [debug] Client->Server compression algorithm: none

[03-09 00:59:15] [debug] (local) Server->Client compression algorithms: none,[e-mail],zlib

[03-09 00:59:15] [debug] (remote) Server->Client compression algorithms: none,[e-mail]

[03-09 00:59:15] [debug] Server->Client compression algorithm: none

[03-09 00:59:15] [debug] Outgoing: Writing KEXECDH_INIT

[03-09 00:59:16] [debug] DEBUG: Checking host key format

[03-09 00:59:16] [debug] DEBUG: Checking signature format

[03-09 00:59:16] [debug] DEBUG: Verifying host fingerprint

[03-09 00:59:16] [debug] DEBUG: Host accepted by default (no verification)

[03-09 00:59:16] [debug] DEBUG: Verifying signature

[03-09 00:59:16] [debug] Outgoing: Writing NEWKEYS

[03-09 00:59:16] [debug] Outgoing: Writing SERVICE_REQUEST (ssh-userauth)

[03-09 00:59:16] [debug] Outgoing: Writing USERAUTH_REQUEST (none)

[03-09 00:59:16] [debug] Client: none auth failed

[03-09 00:59:16] [debug] Outgoing: Writing USERAUTH_REQUEST (password)

[03-09 00:59:16] [debug] Outgoing: Writing CHANNEL_OPEN (0, session)

[03-09 00:59:16] [debug] Outgoing: Writing CHANNEL_REQUEST (0, subsystem: sftp)

[03-09 00:59:16] [debug] Outgoing: Writing CHANNEL_DATA (0)

[03-09 00:59:16] [debug] Outgoing: Writing MKDIR

[03-09 00:59:16] [debug] Outgoing: Writing CHANNEL_DATA (0)

[03-09 00:59:16] [debug] Outgoing: Writing LSTAT

[03-09 00:59:16] [debug] Outgoing: Writing CHANNEL_DATA (0)

[03-09 00:59:16] [debug] Outgoing: Writing OPEN

[03-09 00:59:16] [debug] Outgoing: Writing CHANNEL_DATA (0)

[03-09 00:59:16] [debug] Outgoing: Writing FSTAT

[03-09 00:59:16] [debug] Outgoing: Writing CHANNEL_DATA (0)

[03-09 00:59:16] [debug] Outgoing: Writing FSETSTAT

[03-09 00:59:16] [debug] Outgoing: Writing CHANNEL_DATA (0)

[03-09 00:59:16] [debug] Outgoing: Writing WRITE

[03-09 00:59:16] [debug] Outgoing: Writing CHANNEL_DATA (0)

[03-09 00:59:16] [debug] Outgoing: Writing CHANNEL_DATA (0)

[03-09 00:59:16] [debug] Outgoing: Writing CHANNEL_DATA (0)

[03-09 00:59:16] [debug] Outgoing: Writing WRITE

[03-09 00:59:16] [debug] Outgoing: Writing CHANNEL_DATA (0)

[03-09 00:59:16] [debug] Outgoing: Writing CHANNEL_DATA (0)

[03-09 00:59:16] [debug] Outgoing: Writing CHANNEL_DATA (0)

[03-09 00:59:16] [debug] Outgoing: Writing WRITE

[03-09 00:59:16] [debug] Outgoing: Writing CHANNEL_DATA (0)

[03-09 00:59:16] [debug] Outgoing: Writing CHANNEL_DATA (0)

[03-09 00:59:16] [debug] Outgoing: Writing CHANNEL_DATA (0)

[03-09 00:59:16] [debug] Outgoing: Writing WRITE

[03-09 00:59:16] [debug] Outgoing: Writing CHANNEL_DATA (0)

[03-09 00:59:16] [debug] Outgoing: Writing FSETSTAT

[03-09 00:59:16] [debug] Outgoing: Writing CHANNEL_DATA (0)

[03-09 00:59:16] [debug] Outgoing: Writing CLOSE

[03-09 00:59:16] [debug] Outgoing: Writing CHANNEL_DATA (0)

[03-09 00:59:16] [info] local ➞ remote e:\xxx.js

[03-09 00:59:46] [debug] Outgoing: Writing ping (GLOBAL_REQUEST: [e-mail])

 

有时候点xx.js上传几秒没有反应，这时候又点击上传，有反应了：

03-09 01:05:01] [trace] run command 'Upload File'

[03-09 01:05:01] [trace] run command 'Upload File'

[03-09 01:05:01] [trace] handle upload file fore:\xx.js

[03-09 01:05:01] [trace] handle upload file fore:\xx.js

[03-09 01:05:01] [debug] Outgoing: Writing MKDIR

[03-09 01:05:01] [debug] Outgoing: Writing CHANNEL_DATA (0)

[03-09 01:05:01] [debug] Outgoing: Writing MKDIR

[03-09 01:05:01] [debug] Outgoing: Writing CHANNEL_DATA (0)

[03-09 01:05:01] [debug] Outgoing: Writing LSTAT

[03-09 01:05:01] [debug] Outgoing: Writing CHANNEL_DATA (0)

[03-09 01:05:01] [debug] Outgoing: Writing LSTAT

[03-09 01:05:01] [debug] Outgoing: Writing CHANNEL_DATA (0)

[03-09 01:05:01] [debug] Outgoing: Writing OPEN

[03-09 01:05:01] [debug] Outgoing: Writing CHANNEL_DATA (0)

[03-09 01:05:01] [debug] Outgoing: Writing OPEN

[03-09 01:05:01] [debug] Outgoing: Writing CHANNEL_DATA (0)

[03-09 01:05:01] [debug] Outgoing: Writing FSTAT

[03-09 01:05:01] [debug] Outgoing: Writing CHANNEL_DATA (0)

[03-09 01:05:01] [debug] Outgoing: Writing FSTAT

[03-09 01:05:01] [debug] Outgoing: Writing CHANNEL_DATA (0)

[03-09 01:05:01] [debug] Outgoing: Writing FSETSTAT

[03-09 01:05:01] [debug] Outgoing: Writing CHANNEL_DATA (0)

[03-09 01:05:01] [debug] Outgoing: Writing FSETSTAT

[03-09 01:05:01] [debug] Outgoing: Writing CHANNEL_DATA (0)

[03-09 01:05:01] [debug] Outgoing: Writing WRITE

[03-09 01:05:01] [debug] Outgoing: Writing CHANNEL_DATA (0)

[03-09 01:05:01] [debug] Outgoing: Writing WRITE

[03-09 01:05:01] [debug] Outgoing: Writing CHANNEL_DATA (0)

[03-09 01:05:01] [debug] Outgoing: Writing CHANNEL_DATA (0)

[03-09 01:05:01] [debug] Outgoing: Writing CHANNEL_DATA (0)

[03-09 01:05:01] [debug] Outgoing: Writing WRITE

[03-09 01:05:01] [debug] Outgoing: Writing CHANNEL_DATA (0)

[03-09 01:05:01] [debug] Outgoing: Writing CHANNEL_DATA (0)

[03-09 01:05:01] [debug] Outgoing: Writing CHANNEL_DATA (0)

[03-09 01:05:01] [debug] Outgoing: Writing WRITE

[03-09 01:05:01] [debug] Outgoing: Writing CHANNEL_DATA (0)

[03-09 01:05:01] [debug] Outgoing: Writing CHANNEL_DATA (0)

[03-09 01:05:01] [debug] Outgoing: Writing CHANNEL_DATA (0)

[03-09 01:05:01] [debug] Outgoing: Writing WRITE

[03-09 01:05:01] [debug] Outgoing: Writing CHANNEL_DATA (0)

[03-09 01:05:01] [debug] Outgoing: Writing CHANNEL_DATA (0)

[03-09 01:05:01] [debug] Outgoing: Writing CHANNEL_DATA (0)

[03-09 01:05:01] [debug] Outgoing: Writing WRITE

[03-09 01:05:01] [debug] Outgoing: Writing CHANNEL_DATA (0)

[03-09 01:05:01] [debug] Outgoing: Writing CHANNEL_DATA (0)

[03-09 01:05:01] [debug] Outgoing: Writing CHANNEL_DATA (0)

[03-09 01:05:01] [debug] Outgoing: Writing WRITE

[03-09 01:05:01] [debug] Outgoing: Writing CHANNEL_DATA (0)

[03-09 01:05:01] [debug] Outgoing: Writing CHANNEL_DATA (0)

[03-09 01:05:01] [debug] Outgoing: Writing CHANNEL_DATA (0)

[03-09 01:05:01] [debug] Outgoing: Writing WRITE

[03-09 01:05:01] [debug] Outgoing: Writing CHANNEL_DATA (0)

[03-09 01:05:01] [debug] Outgoing: Writing CHANNEL_DATA (0)

[03-09 01:05:01] [debug] Outgoing: Writing CHANNEL_DATA (0)

[03-09 01:05:01] [debug] Outgoing: Writing WRITE

[03-09 01:05:01] [debug] Outgoing: Writing CHANNEL_DATA (0)

[03-09 01:05:01] [debug] Outgoing: Writing CHANNEL_DATA (0)

[03-09 01:05:01] [debug] Outgoing: Writing CHANNEL_DATA (0)

[03-09 01:05:01] [debug] Outgoing: Writing WRITE

[03-09 01:05:01] [debug] Outgoing: Writing CHANNEL_DATA (0)

[03-09 01:05:01] [debug] Outgoing: Writing CHANNEL_DATA (0)

[03-09 01:05:02] [debug] Outgoing: Writing CHANNEL_DATA (0)

[03-09 01:05:02] [debug] Outgoing: Writing WRITE

[03-09 01:05:02] [debug] Outgoing: Writing CHANNEL_DATA (0)

[03-09 01:05:02] [debug] Outgoing: Writing CHANNEL_DATA (0)

[03-09 01:05:02] [debug] Outgoing: Writing CHANNEL_DATA (0)

 

[03-09 01:05:02] [debug] Outgoing: Writing WRITE

[03-09 01:05:02] [debug] Outgoing: Writing CHANNEL_DATA (0)

[03-09 01:05:02] [debug] Outgoing: Writing FSETSTAT

[03-09 01:05:02] [debug] Outgoing: Writing CHANNEL_DATA (0)

[03-09 01:05:02] [debug] Outgoing: Writing WRITE

[03-09 01:05:02] [debug] Outgoing: Writing CHANNEL_DATA (0)

[03-09 01:05:02] [debug] Outgoing: Writing CLOSE

[03-09 01:05:02] [debug] Outgoing: Writing CHANNEL_DATA (0)

[03-09 01:05:02] [debug] Outgoing: Writing FSETSTAT

[03-09 01:05:02] [debug] Outgoing: Writing CHANNEL_DATA (0)

[03-09 01:05:02] [info] local ➞ remotee:\xx.js

[03-09 01:05:03] [debug] Outgoing: Writing CLOSE

[03-09 01:05:03] [debug] Outgoing: Writing CHANNEL_DATA (0)

[03-09 01:05:03] [info] local ➞ remotee:\xx.js

 

有时候是这里没有反应：

03-09 02:02:07] [debug] Outgoing: Writing ping (GLOBAL_REQUEST: [e-mail])

[03-09 02:02:37] [debug] Outgoing: Writing ping (GLOBAL_REQUEST: [e-mail])

[03-09 02:03:42] [debug] Outgoing: Writing ping (GLOBAL_REQUEST: [e-mail])

[03-09 02:04:36] [debug] Outgoing: Writing ping (GLOBAL_REQUEST: [e-mail])

[03-09 02:06:12] [debug] Outgoing: Writing ping (GLOBAL_REQUEST: [e-mail])

[03-09 02:07:24] [debug] Outgoing: Writing ping (GLOBAL_REQUEST: [e-mail])

[03-09 02:08:38] [debug] Outgoing: Writing ping (GLOBAL_REQUEST: [e-mail])

[03-09 02:09:56] [debug] Outgoing: Writing ping (GLOBAL_REQUEST: [e-mail])

 

 经常是上面这种情况。