Unable to negotiate with Port 22 | No matching key exchange method found

Описание: Unable to negotiate with | No matching key exchange method found
Ubuntu SSH issue
Unable to SSH to the remote Ubuntu machine
Unable to connect to remote Ubuntu machine on port22

Failed to connect to the host via ssh: Unable to negotiate with x.x.x.x port 22: no matching key exchange method found. Their offer: [email protected],curve25519-sha256,[email protected],ecdh-sha2-nistp256,ecdh-sha2-nistp384,ecdh-sha2-nistp521,diffie-hellman-group-exchange-sha256,diffie-hellman-group16-sha512,diffie-hellman-group18-sha512,diffie-hellman-group14-sha256,ext-info-s,[email protected]


1. Allow All Legacy Algorithms

Edit your SSH client config:

sudo nano /etc/ssh/ssh_config


Add (or modify) these lines at the bottom:

Host *
KexAlgorithms +diffie-hellman-group1-sha1,diffie-hellman-group-exchange-sha1,ecdh-sha2-nistp256,ecdh-sha2-nistp384,ecdh-sha2-nistp521,curve25519-sha256
Ciphers +aes128-cbc,3des-cbc,aes256-cbc,aes128-ctr,aes192-ctr,aes256-ctr,[email protected]
MACs +hmac-md5,hmac-sha1,hmac-sha2-256,hmac-sha2-512
HostKeyAlgorithms +ssh-rsa,ssh-dss,ecdsa-sha2-nistp256,ecdsa-sha2-nistp384,ecdsa-sha2-nistp521,ssh-ed25519
StrictHostKeyChecking no
UserKnownHostsFile /dev/null


Meaning:

KexAlgorithms → Accepts weak and modern key exchanges.

Ciphers → Enables older ciphers like AES-CBC and 3DES.

MACs → Allows older message authentication codes.

HostKeyAlgorithms → Accepts even deprecated host key types like ssh-dss and ssh-rsa.

StrictHostKeyChecking no & UserKnownHostsFile /dev/null → Disables host key verification (auto-accept new host keys).