Server responded"Algorithm negotiation failed" Key exchange with the remote host failed. This can happen for example computer does not support the selected algorthms.
When ssh to a ubuntu system,putty can connect but ‘SSH Secure Shell Client’ is failed,according to the pop-up error message we can know that
the algorithm negotiation failed, after searching high-and-low for this fix, I finally found it’s fix…
Because i had past updated server, it’s that means i had updated the sshd algorithm negotiation on server meanwhile, but the sshd algorithm negotiation in client is the old, so server cannot compatible the algorithm negotiation from client.
- Use a different system or the console to drop to a shell. Such as Putty
- Chmod 777 & Edit the “/etc/ssh/sshd_config” file
- Add all of the algorithm negotiation to sshd_config
- Restart sshd sevice
Add following code to sshd_config
Ciphers aes128-cbc,aes192-cbc,aes256-cbc,aes128-ctr,aes192-ctr,aes256-ctr,3des-cbc,arcfour128,arcfour256,arcfour,blowfish-cbc,cast128-cbc MACs hmac-md5,hmac-sha1,email@example.com,hmac-ripemd160,hmac-sha1-96,hmac-md5-96 KexAlgorithms diffie-hellman-group1-sha1,diffie-hellman-group14-sha1,diffie-hellman-group-exchange-sha1,diffie-hellman-group-exchange-sha256,ecdh-sha2-nistp256,ecdh-sha2-nistp384,ecdh-sha2-nistp521,diffie-hellman-group1-sha1,firstname.lastname@example.org
root@ubuntu:/home/app# chmod 777 /etc/ssh/sshd_config root@ubuntu:/home/app# vi /etc/ssh/sshd_config root@ubuntu:/home/app# service sshd restart
Congratulations! you have success resolved Algorithm negotiation failed