# Logon
#
The [Logon ``](https://www.onixs.biz/fix-dictionary/4.4/msgType_A_65.html) message must be the first message sent by the application requesting to initiate a FIX session. The [Logon ``](https://www.onixs.biz/fix-dictionary/4.4/msgType_A_65.html) message authenticates an institution establishing a connection to Gemini.
Upon receipt of a [Logon ``](https://www.onixs.biz/fix-dictionary/4.4/msgType_A_65.html) message, Gemini will authenticate the institution requesting connection by validating the source IP Address, [SenderCompID `<49>`](https://www.onixs.biz/fix-dictionary/4.4/tagNum_49.html), and [TargetCompID `<56>`](https://www.onixs.biz/fix-dictionary/4.4/tagNum_56.html) identifying the institution. The server will then issue a [Logon ``](https://www.onixs.biz/fix-dictionary/4.4/msgType_A_65.html) message as acknowledgment that the connection request has been accepted. The acknowledgment [Logon ``](https://www.onixs.biz/fix-dictionary/4.4/msgType_A_65.html) can also be used by the institution to validate that the connection was established with the correct party. If validation fails, the connection will be dropped without a [Reject `<3>`](https://www.onixs.biz/fix-dictionary/4.4/msgType_3_3.html).
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### FIELDS
| Tag | Name | Req | Description |
| ---- | --------------------------------------------------------------------------- | --- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| | [Standard Header](/trading/fix/overview/standard-header) | Y | [MsgType](https://www.onixs.biz/fix-dictionary/4.4/msgs_by_msg_type.html) = `A` |
| 141 | [ResetSeqNumFlag](https://www.onixs.biz/fix-dictionary/4.4/tagNum_141.html) | N | Should be set to `Y` when the client wants to indicate that both sides of the FIX session should reset sequence numbers. |
| 98 | [EncryptMethod](https://www.onixs.biz/fix-dictionary/4.4/tagNum_98.html) | Y | Gemini does not support encryption.
**Valid value:**
`0 = None` |
| 108 | [HeartBtInt](https://www.onixs.biz/fix-dictionary/4.4/tagNum_108.html) | Y | Heartbeat interval in seconds.
**Valid value:**
`30 = 30 seconds` |
| 9001 | [CancelOnDisconnect](/trading/fix/overview/dictionary/custom-tags) | N | Only used for [Order Entry](/trading/fix/overview/dictionary/version). When present and **true**, orders will be cancelled on disconnect. When present and **false**, orders will not be cancelled on disconnect. When absent, orders will not be cancelled on disconnect.
**Valid values:**
`Y = Enable cancel on disconnect for this session`
`N = Disable cancel on disconnect for this session` |
| | [Standard Trailer](/trading/fix/overview/standard-trailer) | Y | |