サンプルプログラムで println(serverKexinit) とすると, サーバから送られる KEXINIT メッセージがダンプできます. 私の環境での出力を整形したものを示します.
Kexinit(
/* SSH_MSG_KEXINIT */ SSHByte(20),
/* cookie */ (略),
/* kex_algorithms */ SSHNameList(WrappedArray(ecdh-sha2-nistp256, ecdh-sha2-nistp384, ecdh-sha2-nistp521, diffie-hellman-group-exchange-sha256, diffie-hellman-group-exchange-sha1, diffie-hellman-group14-sha1, diffie-hellman-group1-sha1)),
/* server_host_key_algorithms */ SSHNameList(WrappedArray(ssh-rsa, ssh-dss)),
/* encryption_algorithms_client_to_server */ SSHNameList(WrappedArray(aes128-ctr, aes192-ctr, aes256-ctr, arcfour256, arcfour128, aes128-cbc, 3des-cbc, blowfish-cbc, cast128-cbc, aes192-cbc, aes256-cbc, arcfour, rijndael-cbc@lysator.liu.se)),
/* encryption_algorithms_server_to_client */ SSHNameList(WrappedArray(aes128-ctr, aes192-ctr, aes256-ctr, arcfour256, arcfour128, aes128-cbc, 3des-cbc, blowfish-cbc, cast128-cbc, aes192-cbc, aes256-cbc, arcfour, rijndael-cbc@lysator.liu.se)),
/* mac_algorithms_client_to_server */ SSHNameList(WrappedArray(hmac-md5, hmac-sha1, umac-64@openssh.com, hmac-ripemd160, hmac-ripemd160@openssh.com, hmac-sha1-96, hmac-md5-96)),
/* mac_algorithms_server_to_client */ SSHNameList(WrappedArray(hmac-md5, hmac-sha1, umac-64@openssh.com, hmac-ripemd160, hmac-ripemd160@openssh.com, hmac-sha1-96, hmac-md5-96)),
/* compression_algorithms_client_to_server */ SSHNameList(WrappedArray(none, zlib@openssh.com)),
/* compression_algorithms_server_to_client */ SSHNameList(WrappedArray(none, zlib@openssh.com)),
/* languages_client_to_server */ SSHNameList(WrappedArray()),
/* languages_server_to_client */ SSHNameList(WrappedArray()),
/* first_kex_packet_follows */ SSHBoolean(false),
/* 0 (reserved for future extension) */SSHUInt32(0)
)