Re: SERVER_KEXINIT_SENT Error -1009

null@example.com (embhorn) — Mon, 07 Jul 2025 17:29:21 +0000

Hi Ajith,

Is this related to a commercial effort which you have a support contract? If so, please send an email to support@wolfssl.com to open a proper support request.

Thanks,
Eric - wolfSSL Support

SERVER_KEXINIT_SENT Error -1009

null@example.com (ajith.k) — Sat, 05 Jul 2025 15:20:08 +0000

I’m setting up an SSH server on an Integrity OS environment. However, when a client attempts to connect, the server immediately terminates the connection and logs the following error:

accept error: SERVER_KEXINIT_SENT, -1009

The client initiates the connection from a Windows terminal using the command:

ssh -vvv -i ca-key-pkcs8-attribute.der -o MACs=hmac-sha2-256 -p 2222 user@

The SSH server is running SSH-2.0-wolfSSHv1.4.20, while the client uses OpenSSH_for_Windows_9.5p1 with LibreSSL 3.8.2.

Server Log is

1970-01-01 00:08:30 [DEBUG] Leaving DoKexInit(), ret = 0

1970-01-01 00:08:30 [DEBUG] PR3: peerMacSz = 0

1970-01-01 00:08:30 [DEBUG] PR4: Shrinking input buffer

1970-01-01 00:08:30 [DEBUG] Entering ShrinkBuffer()

1970-01-01 00:08:30 [DEBUG]   buf->bufferSz = 1432

1970-01-01 00:08:30 [DEBUG]   buf->idx = 1432

1970-01-01 00:08:30 [DEBUG]   buf->length = 1432

1970-01-01 00:08:30 [DEBUG] SB: usedSz = 0, forcedFree = 1

1970-01-01 00:08:30 [DEBUG] SB: releasing dynamic buffer

1970-01-01 00:08:30 [DEBUG] Leaving ShrinkBuffer()

1970-01-01 00:08:30 [DEBUG] PR5: txCount = 464, rxCount = 1432

1970-01-01 00:08:30 [DEBUG] PR1: size = 8

1970-01-01 00:08:30 [INFO] GID: readjust size

1970-01-01 00:08:30 [DEBUG] Receive: recvd = -1

1970-01-01 00:08:30 [DEBUG] accept error: SERVER_KEXINIT_SENT, -1009

1970-01-01 00:08:30 [DEBUG] Entering wolfSSH_get_error_name()

1970-01-01 00:08:30 [DEBUG] Entering wolfSSH_free()

1970-01-01 00:08:30 [DEBUG] Entering sshResourceFree()

1970-01-01 00:08:30 [DEBUG] Entering ShrinkBuffer()

1970-01-01 00:08:30 [DEBUG]   buf->bufferSz = 16

1970-01-01 00:08:30 [DEBUG]   buf->idx = 0

1970-01-01 00:08:30 [DEBUG]   buf->length = 0

1970-01-01 00:08:30 [DEBUG] SB: usedSz = 0, forcedFree = 1

1970-01-01 00:08:30 [DEBUG] Leaving ShrinkBuffer()

The client log is

debug3: order_hostkeyalgs: no algorithms matched; accept original
debug3: send packet: type 20
debug1: SSH2_MSG_KEXINIT sent
Bad packet length 825833264.
debug2: sshpkt_disconnect: sending SSH2_MSG_DISCONNECT: Packet corrupt
debug3: send packet: type 1
ssh_dispatch_run_fatal: Connection to  port 2222: message authentication code incorrect

wolfSSL - Embedded SSL Library — SERVER_KEXINIT_SENT Error -1009

Re: SERVER_KEXINIT_SENT Error -1009

SERVER_KEXINIT_SENT Error -1009