Otdfbt

I am running Microsoft Windows Server 2019 Datacenter Version 10.0.17763 Build 17763 on Azure and I had SFTP working just fine until EITHER a recent update and reboot on Windows OR an SFTP username (the "vendor1" user) password change on ActiveDirectory clobbered this working install of OpenSSH.

Now when attempting to SFTP from a client machine, all I get is,

Connection reset by xxx.xxx.xxx.xxx port 22

Connection closed

What could be wrong? Has anyone else experienced this and solved it?

Here's my sshd_config file, which was working:

# This is the sshd server system-wide configuration file. See
# sshd_config(5) for more information.

# The strategy used for options in the default sshd_config shipped with
# OpenSSH is to specify options with their default value where
# possible, but leave them commented. Uncommented options override the
# default value.

#Port 22
#AddressFamily any
#ListenAddress 0.0.0.0
#ListenAddress ::

#HostKey __PROGRAMDATA__/ssh/ssh_host_rsa_key
#HostKey __PROGRAMDATA__/ssh/ssh_host_dsa_key
#HostKey __PROGRAMDATA__/ssh/ssh_host_ecdsa_key
#HostKey __PROGRAMDATA__/ssh/ssh_host_ed25519_key

# Ciphers and keying
#RekeyLimit default none

# Logging
#SyslogFacility AUTH
#LogLevel INFO

# Authentication:

#LoginGraceTime 2m
#PermitRootLogin prohibit-password
#StrictModes yes
#MaxAuthTries 6
#MaxSessions 10

#PubkeyAuthentication yes

# The default is to check both .ssh/authorized_keys and .ssh/authorized_keys2
# but this is overridden so installations will only check .ssh/authorized_keys
AuthorizedKeysFile .ssh/authorized_keys

#AuthorizedPrincipalsFile none

# For this to work you will also need host keys in %programData%/ssh/ssh_known_hosts
#HostbasedAuthentication no
# Change to yes if you don't trust ~/.ssh/known_hosts for
# HostbasedAuthentication
#IgnoreUserKnownHosts no
# Don't read the user's ~/.rhosts and ~/.shosts files
#IgnoreRhosts yes

# To disable tunneled clear text passwords, change to no here!
PasswordAuthentication yes
#PermitEmptyPasswords no

#AllowAgentForwarding yes
#AllowTcpForwarding yes
#GatewayPorts no
#PermitTTY yes
#PrintMotd yes
#PrintLastLog yes
#TCPKeepAlive yes
#UseLogin no
#PermitUserEnvironment no
#ClientAliveInterval 0
#ClientAliveCountMax 3
#UseDNS no
#PidFile /var/run/sshd.pid
#MaxStartups 10:30:100
#PermitTunnel no
#ChrootDirectory none
#VersionAddendum none

# no default banner path
Banner F:SFTP-Welcome.txt
#Banner /SFTP-Welcome.txt

# override default of no subsystems
Subsystem sftp sftp-server.exe

# Example of overriding settings on a per-user basis
#Match User anoncvs
# AllowTcpForwarding no
# PermitTTY no
# ForceCommand cvs server

#Match Group administrators
# AuthorizedKeysFile __PROGRAMDATA__/ssh/administrators_authorized_keys

#DenyGroups companyvendors companyauditors
#AllowGroups companyadministrators

Match Group vendors
 ChrootDirectory F:Vendors
 #ChrootDirectory F:Vendors%u
 #ChrootDirectory %h
 ForceCommand internal-sftp
 X11Forwarding no
 AllowTcpForwarding no

# no default banner path
#Banner F:VendorsSFTP-Welcome.txt
#Banner /SFTP-Welcome.txt

Using the -v (verbose) option in my SFTP command (sftp -v vendor1@its.my.ip.addr) yields:

debug1: Authentications that can continue: publickey,password,keyboard-interactive
debug1: Next authentication method: publickey
debug1: Trying private key: C:\Users\mylocalusername/.ssh/id_rsa
debug1: Trying private key: C:\Users\mylocalusername/.ssh/id_dsa
debug1: Trying private key: C:\Users\mylocalusername/.ssh/id_ecdsa
debug1: Trying private key: C:\Users\mylocalusername/.ssh/id_ed25519
debug1: Trying private key: C:\Users\mylocalusername/.ssh/id_xmss
debug1: Next authentication method: keyboard-interactive
debug1: Authentications that can continue: publickey,password,keyboard-interactive
debug1: Next authentication method: password
debug1: read_passphrase: can't open /dev/tty: No such file or directory
vendor1@its.my.ip.addrr's password:
debug1: Authentication succeeded (password).
Authenticated to its.my.ip.addrr ([its.my.ip.addrr]:22).
debug1: channel 0: new [client-session]
debug1: Requesting no-more-sessions@openssh.com
debug1: Entering interactive session.
debug1: pledge: network
Connection reset by its.my.ip.addrr port 22
Connection closed

That user "mylocalusername" is my local client PC Windows login name.