encryption_algorithms_server_to_client for libssh2

[laogaolao]

I am using libcurl based on libssh2, and in libcurl I called the libssh2_session_method_pref to set the crypto, mac and othere security parameter like:

if(libssh2_session_method_pref(sshc->ssh_session, LIBSSH2_METHOD_HOSTKEY, hostAlgo))
{
    failf(data, "Failure libssh2_session_method_pref");
    return CURLE_FAILED_INIT;
}

if(libssh2_session_method_pref(sshc->ssh_session, LIBSSH2_METHOD_MAC_CS, mac))
{
    failf(data, "Failure libssh2_session_method_pref");

    return CURLE_FAILED_INIT;
}

if(libssh2_session_method_pref(sshc->ssh_session, LIBSSH2_METHOD_CRYPT_CS, cipher))
{
    failf(data, "Failure libssh2_session_method_pref");

    return CURLE_FAILED_INIT;
}

if(libssh2_session_method_pref(sshc->ssh_session, LIBSSH2_METHOD_KEX, kexAlg))
{
    failf(data, "Failure libssh2_session_method_pref");
    return CURLE_FAILED_INIT;
}

But when we using tcpdump to capture the package during the sftp connect, the encryption_algorithms_server_to_client show some unexpected algorithm in the Client key exchange Init.
aes128-ctr,aes192-ctr,aes256-ctr,aes256-cbc,[email protected],aes192-cbc,aes128-cbc,blowfish-cbc,arcfour128,arcfour,cast128-cbc,3des-cbc
The encryption_algorithms_client_to_server seems correct: aes128-cbc,aes256-cbc,aes128-ctr,aes256-ctr

I just set the 'aes128-ctr,aes192-ctr,aes256-ctr,aes256-cb' when I called the libssh2_session_method_pref(sshc->ssh_session, LIBSSH2_METHOD_CRYPT_CS, cipher).

So How can I remove the '[email protected],aes192-cbc,aes128-cbc,blowfish-cbc,arcfour128,arcfour,cast128-cbc,3des-cbc' for the libssh2 in the encryption_algorithms_server_to_client? Thanks.

[willco007]

You need to set the server client pref with this key LIBSSH2_METHOD_CRYPT_SC.

[laogaolao]

hi,
Sorry, what does it mean of 'server client pref', could you give more detailed info? Is there other function should be used? Thanks.

[willco007]

Just like what you are doing in your above sample code, but with the "Server Client" preference keys such as LIBSSH2_METHOD_CRYPT_SC as well as the Client Server keys.

[laogaolao]

Oh, got it, thanks