Receiving EnterpriseDT.Net.Ftp.Ssh.SFTPException "socket closed" error when trying to establish an SFTP connection with host. Using this library, we can establish connections to other SFTP hosts with success but it fails when trying to connect to this specific host. Below are the logs from the failure with IP addresses removed. Any help or thought on what could be causing the issue would be greatly appreciated.
INFO [LicenseProperties] 24 Feb 2021 15:21:31.300 : Licence expiry date: 12/31/9999
INFO [LicenseProperties] 24 Feb 2021 15:21:31.301 : Production license
DEBUG [SSHSCPClient] 24 Feb 2021 15:21:31.302 : Setting up fallback kbi prompt based on supplied password
DEBUG [HostNameResolver] 24 Feb 2021 15:21:31.304 : Resolving ftp.epidatacenter.com
DEBUG [HostNameResolver] 24 Feb 2021 15:21:31.369 : Obtained 1 addresses
DEBUG [HostNameResolver] 24 Feb 2021 15:21:31.369 : IP address: XX.XXX.XXX.XXX
DEBUG [HostNameResolver] 24 Feb 2021 15:21:31.369 : ftp.epidatacenter.com resolved to XX.XXX.XXX.XXX
DEBUG [SSHSCPClient] 24 Feb 2021 15:21:31.371 : Connecting directly to SFTP server XX.XXX.XXX.XXX:22
INFO [BaseSocket] 24 Feb 2021 15:21:31.371 : Connecting to XX.XXX.XXX.XXX:22 with timeout 120000 ms
DEBUG [BaseSocket] 24 Feb 2021 15:21:31.465 : Successfully connected to XX.XXX.XXX.XXX:22
DEBUG [SSHSCPClient] 24 Feb 2021 15:21:31.465 : Connected successfully to SFTP server XX.XXX.XXX.XXX:22
DEBUG [SSHConnection] 24 Feb 2021 15:21:31.465 : Beginning protocol negotiation
DEBUG [PlainSocket] 24 Feb 2021 15:21:31.569 : SSHSCPClient.1 RepeatCallback received 30 bytes
DEBUG [ProtocolNegotiationHandler] 24 Feb 2021 15:21:31.571 : SSHSCPClient.1 offset=0,length=30
INFO [ProtocolNegotiationHandler] 24 Feb 2021 15:21:31.571 : SSHSCPClient.1 Server version = 'SSH-2.0-WS_FTP-SSH_8.7.0.105'
DEBUG [SSHUtil] 24 Feb 2021 15:21:31.572 : SSHSCPClient.1 Major string = '2'
DEBUG [SSHUtil] 24 Feb 2021 15:21:31.572 : SSHSCPClient.1 Minor string = '0'
DEBUG [SSHUtil] 24 Feb 2021 15:21:31.572 : SSHSCPClient.1 Version 2.0
DEBUG [SSHUtil] 24 Feb 2021 15:21:31.572 : SSHSCPClient.1 Protocol compatible
DEBUG [SSHConnection] 24 Feb 2021 15:21:31.572 : Server version=SSH-2.0-WS_FTP-SSH_8.7.0.105
DEBUG [SSH2Connection] 24 Feb 2021 15:21:31.573 : Timeout=120000
DEBUG [SSHConnection] 24 Feb 2021 15:21:31.574 : Sending client version=SSH-2.0-edtFTPnet/PRO_9.1.0.20
DEBUG [SSH2Connection] 24 Feb 2021 15:21:31.575 : Starting key exchange
DEBUG [AbstractKeyExchanger] 24 Feb 2021 15:21:31.576 : Sending SSH_MSG_KEXINIT
DEBUG [AbstractKeyExchanger] 24 Feb 2021 15:21:31.577 : key exchange method=diffie-hellman-group1-sha1,diffie-hellman-group14-sha1,diffie-hellman-group-exchange-sha1,diffie-hellman-group-exchange-sha256
DEBUG [AbstractKeyExchanger] 24 Feb 2021 15:21:31.578 : hostkey algorithms=ssh-dss,ssh-rsa
DEBUG [AbstractKeyExchanger] 24 Feb 2021 15:21:31.579 : ciphers=blowfish-cbc,aes128-cbc,aes192-cbc,aes256-cbc,3des-cbc,aes128-ctr,aes192-ctr,aes256-ctr
DEBUG [AbstractKeyExchanger] 24 Feb 2021 15:21:31.579 : ciphers=blowfish-cbc,aes128-cbc,aes192-cbc,aes256-cbc,3des-cbc,aes128-ctr,aes192-ctr,aes256-ctr
DEBUG [AbstractKeyExchanger] 24 Feb 2021 15:21:31.580 : MACs=hmac-sha1,hmac-md5,hmac-sha1-96,hmac-md5-96,hmac-sha2-256,hmac-sha2-512
DEBUG [AbstractKeyExchanger] 24 Feb 2021 15:21:31.580 : MACs=hmac-sha1,hmac-md5,hmac-sha1-96,hmac-md5-96,hmac-sha2-256,hmac-sha2-512
DEBUG [AbstractKeyExchanger] 24 Feb 2021 15:21:31.580 : compression algorithms=none,zlib
DEBUG [AbstractKeyExchanger] 24 Feb 2021 15:21:31.581 : compression algorithms=none,zlib
DEBUG [AbstractKeyExchanger] 24 Feb 2021 15:21:31.583 : Sent SSH_MSG_KEXINIT
DEBUG [ClientKeyExchanger] 24 Feb 2021 15:21:31.583 : Reading SSH_MSG_KEXINIT reply
DEBUG [SSH2Connection] 24 Feb 2021 15:21:31.584 : Waiting for packet
DEBUG [PlainSocket] 24 Feb 2021 15:21:31.658 : SSHSCPClient.1 RepeatCallback received 384 bytes
DEBUG [SSH2Connection] 24 Feb 2021 15:21:31.660 : Packet arrived
DEBUG [AbstractKeyExchanger] 24 Feb 2021 15:21:31.662 : Processing SSH_MSG_KEXINIT reply
DEBUG [AbstractKeyExchanger] 24 Feb 2021 15:21:31.662 : Remote kex alg=diffie-hellman-group-exchange-sha256,diffie-hellman-group14-sha256
DEBUG [AbstractKeyExchanger] 24 Feb 2021 15:21:31.663 : Decided kex alg= DiffieHellmanGroupExchangeSha256
DEBUG [AbstractKeyExchanger] 24 Feb 2021 15:21:31.663 : Remote hostkey alg=ssh-dss,ssh-rsa
DEBUG [AbstractKeyExchanger] 24 Feb 2021 15:21:31.663 : Decided hostkey alg= DSA
DEBUG [ClientKeyExchanger] 24 Feb 2021 15:21:31.664 : Remote Cipher CS=aes256-ctr,aes192-ctr,aes128-ctr
DEBUG [ClientKeyExchanger] 24 Feb 2021 15:21:31.664 : Decided Cipher C->S= AES_CTR_128
DEBUG [ClientKeyExchanger] 24 Feb 2021 15:21:31.664 : Remote Cipher SC=aes256-ctr,aes192-ctr,aes128-ctr
DEBUG [ClientKeyExchanger] 24 Feb 2021 15:21:31.664 : Decided Cipher S->C= AES_CTR_128
DEBUG [ClientKeyExchanger] 24 Feb 2021 15:21:31.664 : Remote MAC CS=hmac-sha2-256,hmac-sha1,hmac-sha2-384,hmac-sha2-512
DEBUG [ClientKeyExchanger] 24 Feb 2021 15:21:31.665 : Decided MAC C->S= HMAC_SHA1
DEBUG [ClientKeyExchanger] 24 Feb 2021 15:21:31.665 : Remote MAC SC=hmac-sha2-256,hmac-sha1,hmac-sha2-384,hmac-sha2-512
DEBUG [ClientKeyExchanger] 24 Feb 2021 15:21:31.665 : Decided MAC S->C= HMAC_SHA1
DEBUG [ClientKeyExchanger] 24 Feb 2021 15:21:31.665 : Remote Comp CS=none
DEBUG [ClientKeyExchanger] 24 Feb 2021 15:21:31.665 : Decided Comp C->S=None
DEBUG [ClientKeyExchanger] 24 Feb 2021 15:21:31.665 : Remote Comp SC=none
DEBUG [ClientKeyExchanger] 24 Feb 2021 15:21:31.665 : Decided Comp S->C=None
DEBUG [ClientKeyExchanger] 24 Feb 2021 15:21:31.665 : first_kex_packet_follows=False
DEBUG [AbstractKeyExchanger] 24 Feb 2021 15:21:31.665 : Processed SSH_MSG_KEXINIT reply
DEBUG [ClientKeyExchanger] 24 Feb 2021 15:21:31.665 : Sending SSH_MSG_KEX_DH_GEX_REQUEST_OLD
DEBUG [AbstractKeyExchanger] 24 Feb 2021 15:21:31.666 : DH_PREFERRED_GROUP_SIZE=1024
DEBUG [ClientKeyExchanger] 24 Feb 2021 15:21:31.666 : Sent SSH_MSG_KEX_DH_GEX_REQUEST_OLD
DEBUG [SSH2Connection] 24 Feb 2021 15:21:31.666 : Waiting for packet
DEBUG [PlainSocket] 24 Feb 2021 15:21:31.756 : SSHSCPClient.1 RepeatCallback received 0 bytes
DEBUG [SSH2Connection] 24 Feb 2021 15:21:31.756 : Packet arrived
ERROR [SSH2Connection] 24 Feb 2021 15:21:31.756 : ReceiverState: Closed
ERROR [SSHFTPClient] 24 Feb 2021 15:21:31.757 : Failed to connect - closing connection
ERROR [SSHFTPClient] 24 Feb 2021 15:21:31.757 : EnterpriseDT.Net.Ftp.Ssh.SFTPException: socket closed
ERROR [SSHFTPClient] 24 Feb 2021 15:21:31.757 : at EnterpriseDT.Net.Ftp.Ssh.SSHFTPClient.Connect()
