public static byte[] GetAuthenticationData(TacacsAuthenticationService service, string user,
SecureString password)
{
var userBuf = user.GetUserBuffer();
var authenticationHeader = new TacacsAuthenticationRequestHeader()
{
Action = TacacsAction.Login,
PrivilegeLevel = 0x01,
AuthenticationType = TacacsAuthenticationType.MsChap,
Service = service,
UserLength = ((byte)userBuf.Length),
PortLength = ((byte)ClientPortName.Length),
RemoteLength = 0x00, // optional -- excluded
DataLength = 0x42 // 66 bytes
};
var challenge = new byte[8];
Rng.GetBytes(challenge, 0, 8);
var lmChallengeResponse = GetLmChallengeResponse(challenge, password);
var ntChallengeResponse = GetNtChallengeResponse(challenge, password);
// MS-CHAPv1 response (49 bytes) -- see RFC 2433
var challengeResponse = new byte[49];
Buffer.BlockCopy(lmChallengeResponse, 0, challengeResponse, 0, 24);
Buffer.BlockCopy(ntChallengeResponse, 0, challengeResponse, 24, 24);
Buffer.BlockCopy(new byte[] { 0x01 }, 0, challengeResponse, 48, 1);
// ppp id
var identifier = new byte[1];
Rng.GetBytes(identifier, 0, 1);
// draft 18 -- 5.4.2.4
var data = new byte[66];
Buffer.BlockCopy(identifier, 0, data, 0, 1);
Buffer.BlockCopy(challenge, 0, data, 1, 16);
Buffer.BlockCopy(challengeResponse, 0, data, 17, 49);
// tacacs data
var authenticationDataLength =
8 /* header */ + userBuf.Length + ClientPortName.Length + 0 /* remote */ + 66 /* MsChapV2 length */;
var authenticationData = new byte[authenticationDataLength];
var headerBuf = StructConverter.StructToBytes(authenticationHeader);
Buffer.BlockCopy(headerBuf, 0, authenticationData, 0, 8);
Buffer.BlockCopy(userBuf, 0, authenticationData, 8, userBuf.Length);
Buffer.BlockCopy(ClientPortName, 0, authenticationData, 8 + userBuf.Length, ClientPortName.Length);
Buffer.BlockCopy(data, 0, authenticationData, 8 + userBuf.Length + ClientPortName.Length, data.Length);
return(authenticationData);
}
public static byte[] GetAuthenticationPacket(TacacsAuthenticationType type, TacacsAuthenticationService service,
string user, SecureString password,
SecureString sharedSecret)
{
byte[] intBuf = { 0x00, 0x00, 0x00, 0x00 };
Rng.GetBytes(intBuf, 0, 4);
var sessionId = BitConverter.ToInt32(intBuf, 0);
var header = new TacacsHeader
{
Version = TacacsHeaderExtensions.VersionOne,
Type = TacacsType.Authentication,
SequenceNumber = 0x01,
Flags = TacacsFlags.Encrypted,
SessionId = sessionId,
Length = 0
};
byte[] authenticationData;
switch (type)
{
case TacacsAuthenticationType.Ascii:
throw new NotSupportedException("ASCII authentication method not supported");
case TacacsAuthenticationType.Pap:
throw new NotSupportedException("PAP authentication method not supported");
case TacacsAuthenticationType.Arap:
throw new NotSupportedException("ARAP authentication method not supported");
case TacacsAuthenticationType.MsChap:
throw new NotSupportedException("MS-CHAP authentication method not supported");
case TacacsAuthenticationType.Chap:
authenticationData = Chap.GetAuthenticationData(service, user, password);
break;
case TacacsAuthenticationType.MsChapV2:
authenticationData = MsChapV2.GetAuthenticationData(service, user, password);
break;
default:
throw new ArgumentOutOfRangeException(nameof(type), type, null);
}
return(CreatePacket(header, authenticationData, sharedSecret));
}
public static byte[] GetAuthenticationData(TacacsAuthenticationService service, string user,
SecureString password)
{
var userBuf = user.GetUserBuffer();
var authenticationHeader = new TacacsAuthenticationRequestHeader()
{
Action = TacacsAction.Login,
PrivilegeLevel = 0x01,
AuthenticationType = TacacsAuthenticationType.Chap,
Service = service,
UserLength = ((byte)userBuf.Length),
PortLength = ((byte)ClientPortName.Length),
RemoteLength = 0x00, // optional -- excluded
DataLength = 0x42 // 66 bytes -- big challenge
};
var identifier = new byte[1];
Rng.GetBytes(identifier, 0, 1);
//var challenge = new byte[49];
//Rng.GetBytes(challenge, 0, 32);
var challenge = Encoding.ASCII.GetBytes("1234567890123456789012345678901234567890123456789");
var response = GetResponse(identifier, challenge, password);
var data = new byte[1 /* identifier */ + 49 /* challenge */ + 16 /* response */];
Buffer.BlockCopy(identifier, 0, data, 0, 1);
Buffer.BlockCopy(challenge, 0, data, 1, 49);
Buffer.BlockCopy(response, 0, data, 50, 16);
var authenticationDataLength =
8 /* header */ + userBuf.Length + ClientPortName.Length + 0 /* remote */ + 66 /* CHAP length */;
var authenticationData = new byte[authenticationDataLength];
var headerBuf = StructConverter.StructToBytes(authenticationHeader);
Buffer.BlockCopy(headerBuf, 0, authenticationData, 0, 8);
Buffer.BlockCopy(userBuf, 0, authenticationData, 8, userBuf.Length);
Buffer.BlockCopy(ClientPortName, 0, authenticationData, 8 + userBuf.Length, ClientPortName.Length);
Buffer.BlockCopy(data, 0, authenticationData, 8 + userBuf.Length + ClientPortName.Length, data.Length);
return(authenticationData);
}
public bool Authenticate(TacacsAuthenticationType type, TacacsAuthenticationService service, string user,
SecureString password)
{
if (string.IsNullOrEmpty(user))
{
throw new ArgumentException("Must specify a valid user name", nameof(user));
}
if (password == null)
{
throw new ArgumentException("Must specify a valid password", nameof(password));
}
var requestPacket = TacacsPlusProtocol.GetAuthenticationPacket(type, service, user, password, _sharedSecret);
var responsePacket = SendReceive(requestPacket);
var responsePayload = ValidateResponseAndGetPayload(responsePacket);
var authenticationReplyHeader =
StructConverter.BytesToStruct <TacacsAuthenticationReplyHeader>(responsePayload);
switch (authenticationReplyHeader.Status)
{
case TacacsAuthenticationStatus.Pass:
return(true);
case TacacsAuthenticationStatus.Fail:
return(false);
case TacacsAuthenticationStatus.Error:
var serverMessage =
Encoding.UTF8.GetString(responsePacket.Skip(6 /* Authentication Reply Header Size */)
.Take(authenticationReplyHeader.ServerMessageLength).ToArray());
throw new Exception($"Server responded with an error: {serverMessage}");
default:
throw new Exception($"Unexpected authentication status: {authenticationReplyHeader.Status}");
}
}
public static byte[] GetAuthenticationData(TacacsAuthenticationService service, string user,
SecureString password)
{
var userBuf = user.GetUserBuffer();
var authenticationHeader = new TacacsAuthenticationRequestHeader()
{
Action = TacacsAction.Login,
PrivilegeLevel = 0x01,
AuthenticationType = TacacsAuthenticationType.MsChapV2,
Service = service,
UserLength = ((byte)userBuf.Length),
PortLength = ((byte)ClientPortName.Length),
RemoteLength = 0x00, // optional -- excluded
DataLength = 0x42 // 66 bytes
};
var authenticatorChallenge = new byte[16];
var peerChallenge = new byte[16];
Rng.GetBytes(authenticatorChallenge, 0, 16);
Rng.GetBytes(peerChallenge, 0, 16);
// see RFC 2433
var challengeResponse = new byte[49];
// challenge -- 16 bytes
Buffer.BlockCopy(peerChallenge, 0, challengeResponse, 0, 16);
// reserved -- 8 bytes (zeroes)
for (var i = 16; i < 24; i++)
{
Buffer.SetByte(challengeResponse, i, 0x00);
}
// NT-response -- 24 bytes
var ntResponse = GetNtResponse(authenticatorChallenge, peerChallenge, userBuf, password);
Buffer.BlockCopy(ntResponse, 0, challengeResponse, 24, 24);
// flags -- 1 byte (zero)
Buffer.SetByte(challengeResponse, 48, 0);
var identifier = new byte[1];
Rng.GetBytes(identifier, 0, 1);
// draft 18 -- 5.4.2.5
var data = new byte[66];
Buffer.BlockCopy(identifier, 0, data, 0, 1);
Buffer.BlockCopy(authenticatorChallenge, 0, data, 1, 16);
Buffer.BlockCopy(challengeResponse, 0, data, 17, 49);
// tacacs data
var authenticationDataLength =
8 /* header */ + userBuf.Length + ClientPortName.Length + 0 /* remote */ + 66 /* MsChapV2 length */;
var authenticationData = new byte[authenticationDataLength];
var headerBuf = StructConverter.StructToBytes(authenticationHeader);
Buffer.BlockCopy(headerBuf, 0, authenticationData, 0, 8);
Buffer.BlockCopy(userBuf, 0, authenticationData, 8, userBuf.Length);
Buffer.BlockCopy(ClientPortName, 0, authenticationData, 8 + userBuf.Length, ClientPortName.Length);
Buffer.BlockCopy(data, 0, authenticationData, 8 + userBuf.Length + ClientPortName.Length, data.Length);
return(authenticationData);
}
