Connecting

Connection is done by many exchanges:

  • (Create socket)
  • Server sends Initial handshake packet
  • If SSL/TLS connection
    • Client sends SSLRequest packet and switches to SSL mode for sending and receiving the following messages:
  • Client sends Handshake response packet
  • Server sends either:
    • An OK packet in case of success OK_Packet
    • An error packet in case of error ERR_Packet
    • Authentication switch
      • If the client or server doesn't have PLUGIN_AUTH capability:
        • Server sends 0xFE byte
        • Client sends old_password
      • else
      • Authentication switch ends with server sending either OK_Packet or ERR_Packet



Initial Handshake Packet

  • int<1> protocol version
  • string<NUL> server version (MariaDB server version is by default prefixed by "5.5.5-")
  • int<4> connection id
  • string<8> scramble 1st part (authentication seed)
  • string<1> reserved byte
  • int<2> server capabilities (1st part)
  • int<1> server default collation
  • int<2> status flags
  • int<2> server capabilities (2nd part)
  • if (server_capabilities & PLUGIN_AUTH)
  • else
  • string<6> filler
  • if (server_capabilities & CLIENT_MYSQL)
  • else
  • if (server_capabilities & CLIENT_SECURE_CONNECTION)
    • string<n> scramble 2nd part . Length = max(12, plugin data length - 9)
    • string<1> reserved byte
  • if (server_capabilities & PLUGIN_AUTH)



Client Handshake Response

If the client requests a TLS/SSL connection, first response will be an SSL connection request packet, then a handshake response packet. If no TLS is required, client send directly a handshake response packet.

SSLRequest Packet



Handshake Response Packet

  • int<4> client capabilities
  • int<4> max packet size
  • int<1> client character collation
  • string<19> reserved
  • if not (server_capabilities & CLIENT_MYSQL)
    • int<4> extended client capabilities
  • else
  • string<NUL> username
  • if (server_capabilities & PLUGIN_AUTH_LENENC_CLIENT_DATA)
  • else if (server_capabilities & CLIENT_SECURE_CONNECTION)
    • int<1> length of authentication response
    • string<fix> authentication response (length is indicated by previous field)
  • else
  • if (server_capabilities & CLIENT_CONNECT_WITH_DB)
  • if (server_capabilities & CLIENT_PLUGIN_AUTH)
  • if (server_capabilities & CLIENT_CONNECT_ATTRS)

Authentication Switch Request

(If client and server support CLIENT_AUTH capability)



Plugin List



mysql_old_password Plugin

deprecated
send a 8 byte encrypted password

authentication plugin data format :

Client response :



mysql_clear_password Plugin

Since password is transmitted in clear, this has be used only when using SSL connection

send clear password to server

Client response :



mysql_native_password Plugin

SHA-1 encrypted password with server seed

authentication plugin data format :

Client response :

The password is encrypted with: SHA1( password ) ^ SHA1( seed + SHA1( SHA1( password ) ) )



dialog Plugin (PAM)

Interactive exchanges to permit fill passwords - for example for 2-Step authentication.

authentication plugin data format :

The server can send one or many requests. For each of them, the client must display this prompt message to the user, to permit the user to type requested information, then send it to the server in string<NUL> format. Password type indicate answer format ( 2 means "read the input with the echo enabled", 4 means "password-like input, echo disabled")

First authentication format (from authentication switch packet) can be empty since 10.4.

This end when server send an EOF_Packet, OK_Packet or ERROR_packet.



auth_gssapi_client Plugin

gssapi implementation

authentication plugin data format :

Client must exchange packet with server until having a mutual GSSAPI authentication. The only difference compared to standard client-server GSSAPI authentication is that exchanges contain standard protocol with packet headers.



client_ed25519 Plugin

The ed25519 plugin uses the Elliptic Curve Digital Signature Algorithm to securely store users' passwords and to authenticate users. It has been Implemented in the server since MariaDB 10.1.22.

See plugin description.

Client response :



Capabilities

Server and Client have different capabilities, here is the possibles values.
client with capabilities CLIENT_MYSQL + CONNECT_WITH_DB will have a value of 9 (1 + 8).

CLIENT_MYSQL1
FOUND_ROWS2
CONNECT_WITH_DB8One can specify db on connect
COMPRESS32Can use compression protocol
LOCAL_FILES128Can use LOAD DATA LOCAL
IGNORE_SPACE256Ignore spaces before '('
CLIENT_PROTOCOL_411 << 94.1 protocol
CLIENT_INTERACTIVE1 << 10
SSL1 << 11Can use SSL
TRANSACTIONS1 << 12
SECURE_CONNECTION1 << 134.1 authentication
MULTI_STATEMENTS1 << 16Enable/disable multi-stmt support
MULTI_RESULTS1 << 17Enable/disable multi-results
PS_MULTI_RESULTS1 << 18Enable/disable multi-results for PrepareStatement
PLUGIN_AUTH1 << 19Client supports plugin authentication
CONNECT_ATTRS1 << 20Client send connection attributes
PLUGIN_AUTH_LENENC_CLIENT_DATA1 << 21Enable authentication response packet to be larger than 255 bytes
CLIENT_SESSION_TRACK1 << 23Enable/disable session tracking in OK_Packet
CLIENT_DEPRECATE_EOF1 << 24EOF_Packet deprecation :
* OK_Packet replace EOF_Packet in end of Resulset when in text format
* EOF_Packet between columns definition and resultsetRows is deleted
CLIENT_ZSTD_COMPRESSION_ALGORITHM1 << 26Support zstd protocol compression
CLIENT_CAPABILITY_EXTENSION1 << 29reserved for futur use. (Was CLIENT_PROGRESS Client support progress indicator before 10.2)
MARIADB_CLIENT_PROGRESS1 << 32Client support progress indicator (since 10.2)
MARIADB_CLIENT_COM_MULTI1 << 33Permit COM_MULTI protocol
MARIADB_CLIENT_STMT_BULK_OPERATIONS1 << 34Permit bulk insert
MARIADB_CLIENT_EXTENDED_TYPE_INFO1 << 35add extended metadata information


Native Password Authentication

The 20 byte string 'seed' is calculated by concatenating scramble first part (8 bytes) and scramble second part from Initial handshake packet. After that, the client calculates a password hash using the password and seed by using ^ (bitwise xor), + (string concatenation) and SHA1 as follows:

SHA1( passwd) ^ SHA1( seed + SHA1( SHA1( passwd ) ) )

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