As you are using the
Net::SSH2 backend, you should check what
libssh2 supports:
Key Exchange Methods: diffie-hellman-group1-sha1, diffie-hellman-group
+14-sha1, diffie-hellman-group-exchange-sha1,
diffie-hellman-group-exchange-sha256
Hostkey Types: ssh-rsa, ssh-dss
Ciphers: aes256-ctr, aes192-ctr, aes128-ctr, aes256-cbc (rijndael-cbc@
+lysator.liu.se), aes192-cbc, aes128-cbc,
3des-cbc, blowfish-cbc, cast128-cbc, arcfour, arcfour128, non
+e
You should also ensure that you are using a recent version of the library. Probably 1.8.2 which was released some days ago and incorporates several important security fixes.
In any case, you should probably check yourself if it works for your particular configuration as libssh2 is quite buggy.