SSH protocol Error Messages
The Secure Shell protocol itself.All SSH protocol pages
- Unable to negotiate with HOST port 22: no matching host key type found. Their offer: ssh-rsaOpenSSH 8.8+ disables ssh-rsa SHA-1 signatures, so old servers fail with no matching host key type found. Upgrade them or allow +ssh-rsa for that host only.
- Unable to negotiate: no matching cipher found. Their offer: aes128-cbc,3des-cbcThe SSH server offers only CBC or 3DES ciphers that current OpenSSH clients do not enable by default. Upgrade it, or add Ciphers +aes128-cbc for that one host.
- Unable to negotiate: no matching key exchange method found. Their offer: diffie-hellman-group1-sha1The SSH server offers only old key exchange such as diffie-hellman-group1-sha1. Upgrade it, or enable that algorithm for this one host with KexAlgorithms +.
- Unable to negotiate: no matching MAC found. Their offer: hmac-md5,hmac-sha1-96The SSH server offers only old MACs such as hmac-md5 or hmac-sha1-96. Upgrade the server, or enable one offered MAC for that host only with MACs +ALGORITHM.