Newer SSH client cannot connect to older SSH server (dropbear openwrt) because:
The RSA SHA-1 hash algorithm is being quickly deprecated across operating systems and SSH clients because of various security vulnerabilities, with many of these technologies now outright denying the use of this algorithm.
error message: no mutual signature algorithm
edit /etc/ssh/ssh_config
HostKeyAlgorithms=+ssh-rsa
PubkeyAuthentication yes
PubkeyAcceptedKeyTypes=+ssh-rsa
error message: no matching key exchange method found. Their offer: diffie-hellman-group1-sha1,diffie-hellman-group14-sha1,kexguess2@matt.ucc.asn.au
Windows, the OpenSSH Client (ssh) reads configuration data from a configuration file in the following order:
By launching ssh.exe with the -F parameter, specifying a path to a configuration file and an entry name from that file.
A user's configuration file at %userprofile%\.ssh\config.
The system-wide configuration file at %programdata%\ssh\ssh_config.The OpenSSH website has a page dedicated to legacy issues such as this one. It suggests the following approach, on the client:
ssh -oKexAlgorithms=+diffie-hellman-group1-sha1 123.123.123.123
or more permanently, adding
Host 123.123.123.123
KexAlgorithms +diffie-hellman-group1-sha1
The OpenSSH website has a page dedicated to legacy issues such as this one. It suggests the following approach, on the client:
ssh -oKexAlgorithms=+diffie-hellman-group1-sha1 123.123.123.123
or more permanently, adding
Host 123.123.123.123
KexAlgorithms +diffie-hellman-group1-sha1
to ~/.ssh/config
https://confluence.atlassian.com/bitbucketserverkb/ssh-rsa-key-rejected-with-message-no-mutual-signature-algorithm-1026057701.html
https://learn.microsoft.com/en-us/windows-server/administration/openssh/openssh_server_configuration
https://unix.stackexchange.com/questions/340844/how-to-enable-diffie-hellman-group1-sha1-key-exchange-on-debian-8-0