解决MacOS SSH Error “no matching key exchange method found. ..”

问题描述：

在Mac OS 系统中，当我们使用Terminal通过ssh去连接一个远程主机，可能会遇到以下报错：

JUNLI5-M-R24U:~ junli$ ssh [email protected]
Unable to negotiate with 10.75.169.43 port 22: no matching key exchange method found. Their offer: diffie-hellman-group1-sha1

解决方案

Terminal找不到支持的密钥交换方法，因为新版Openssh中认为SHA1这种hash散列算法过于薄弱，已经不再支持，所以我们需要手动去enable对于SHA1的支持：

JUNLI5-M-R24U:ssh junli$ vim /etc/ssh/ssh_config
取消注释这一行内容：   MACs hmac-md5,hmac-sha1,[email protected],hmac-ripemd160
并且在文件结尾添加：
HostkeyAlgorithms ssh-dss,ssh-rsa
KexAlgorithms +diffie-hellman-group1-sha1

编辑后/etc/ssh/ssh_config完整的文件内容如下：

#   $OpenBSD: ssh_config,v 1.30 2016/02/20 23:06:23 sobrado Exp $

# This is the ssh client system-wide configuration file.  See
# ssh_config(5) for more information.  This file provides defaults for
# users, and the values can be changed in per-user configuration files
# or on the command line.

# Configuration data is parsed as follows:
#  1. command line options
#  2. user-specific file
#  3. system-wide file
# Any configuration value is only changed the first time it is set.
# Thus, host-specific definitions should be at the beginning of the
# configuration file, and defaults at the end.

# Site-wide defaults for some commonly used options.  For a comprehensive
# list of available options, their meanings and defaults, please see the
# ssh_config(5) man page.

# Host *
#   ForwardAgent no
#   ForwardX11 no
#   RhostsRSAAuthentication no
#   RSAAuthentication yes
#   PasswordAuthentication yes
#   HostbasedAuthentication no
#   GSSAPIAuthentication no
#   GSSAPIDelegateCredentials no
#   BatchMode no
#   CheckHostIP yes
#   AddressFamily any
#   ConnectTimeout 0
#   StrictHostKeyChecking ask
#   IdentityFile ~/.ssh/identity
#   IdentityFile ~/.ssh/id_rsa
#   IdentityFile ~/.ssh/id_dsa
#   IdentityFile ~/.ssh/id_ecdsa
#   IdentityFile ~/.ssh/id_ed25519
#   Port 22
#   Protocol 2
#   Cipher 3des
#   Ciphers aes128-ctr,aes192-ctr,aes256-ctr,arcfour256,arcfour128,aes128-cbc,3des-cbc
   MACs hmac-md5,hmac-sha1,[email protected],hmac-ripemd160
#   EscapeChar ~
#   Tunnel no
#   TunnelDevice any:any
#   PermitLocalCommand no
#   VisualHostKey no
#   ProxyCommand ssh -q -W %h:%p gateway.example.com
#   RekeyLimit 1G 1h
HostkeyAlgorithms ssh-dss,ssh-rsa
KexAlgorithms +diffie-hellman-group1-sha1

配置完无需重启。

参考自：https://www.petenetlive.com/KB/Article/0001245