Connection closed when trying to connect to sftp server. Match group issue?

Question

I'm trying to connect to an Ubuntu server 14.04 LTS with the following command: sftp -P xx user@host (the ssh-server is configured to listen to a different port). The user I'm trying to login with, is the main user account on the server (the one I gave up during the installation of the server). Everytime I try to connect to the server using sftp I get the message Connection closed.

I'm pretty sure it has got something to do with some additions I made in sshd_config, but I don't see where it is going wrong. Here's the whole sshd_config:

# Package generated configuration file
# See the sshd_config(5) manpage for details

# What ports, IPs and protocols we listen for
Port 2222
# Use these options to restrict which interfaces/protocols sshd will bind to
#ListenAddress ::
#ListenAddress 0.0.0.0
Protocol 2
# HostKeys for protocol version 2
HostKey /etc/ssh/ssh_host_rsa_key
HostKey /etc/ssh/ssh_host_dsa_key
HostKey /etc/ssh/ssh_host_ecdsa_key
HostKey /etc/ssh/ssh_host_ed25519_key
#Privilege Separation is turned on for security
UsePrivilegeSeparation yes

# Lifetime and size of ephemeral version 1 server key
KeyRegenerationInterval 3600
ServerKeyBits 1024

# Logging
SyslogFacility AUTH
LogLevel INFO

# Authentication:
LoginGraceTime 120
PermitRootLogin without-password
StrictModes yes

RSAAuthentication yes
PubkeyAuthentication yes
#AuthorizedKeysFile     %h/.ssh/authorized_keys

# Don't read the user's ~/.rhosts and ~/.shosts files
IgnoreRhosts yes
# For this to work you will also need host keys in /etc/ssh_known_hosts
RhostsRSAAuthentication no
# similar for protocol version 2
HostbasedAuthentication no
# Uncomment if you don't trust ~/.ssh/known_hosts for RhostsRSAAuthentication
#IgnoreUserKnownHosts yes

# To enable empty passwords, change to yes (NOT RECOMMENDED)
PermitEmptyPasswords no

# Change to yes to enable challenge-response passwords (beware issues with
# some PAM modules and threads)
ChallengeResponseAuthentication no

# Change to no to disable tunnelled clear text passwords
PasswordAuthentication no

# Kerberos options
#KerberosAuthentication no
#KerberosGetAFSToken no
#KerberosOrLocalPasswd yes
#KerberosTicketCleanup yes

# GSSAPI options
#GSSAPIAuthentication no
#GSSAPICleanupCredentials yes

X11Forwarding yes
X11DisplayOffset 10
PrintMotd no
PrintLastLog yes
TCPKeepAlive yes
#UseLogin no

#MaxStartups 10:30:60
#Banner /etc/issue.net

# Allow client to pass locale environment variables
AcceptEnv LANG LC_*

Subsystem sftp internal- sftp

# Set this to 'yes' to enable PAM authentication, account processing,
# and session processing. If this is enabled, PAM authentication will
# be allowed through the ChallengeResponseAuthentication and
# PasswordAuthentication.  Depending on your PAM configuration,
# PAM authentication via ChallengeResponseAuthentication may bypass
# the setting of "PermitRootLogin without-password".
# If you just want the PAM account and session checks to run without
# PAM authentication, then enable this but set PasswordAuthentication
# and ChallengeResponseAuthentication to 'no'.
UsePAM yes

Match Group sftpusers
        ChrootDirectory /var/www/Vassens
        # XllForwarding no
        AllowTcpForwarding no
        ForceCommand internal-sftp

The main user account I'm trying to login with is not a member of the 'sftpusers' group. I've been able to login as another user who is a member of 'sftpusers'.

This is what happens after a successful authentication when I'm trying to connect:

debug1: channel 0: new [client-session]
debug1: Requesting [email protected]
debug1: Entering interactive session.
debug1: Sending environment.
debug1: Sending env LC_PAPER = nl_NL.UTF-8
debug1: Sending env LC_ADDRESS = nl_NL.UTF-8
debug1: Sending env LC_MONETARY = nl_NL.UTF-8
debug1: Sending env LC_NUMERIC = nl_NL.UTF-8
debug1: Sending env LC_TELEPHONE = nl_NL.UTF-8
debug1: Sending env LC_IDENTIFICATION = nl_NL.UTF-8
debug1: Sending env LANG = en_US.UTF-8
debug1: Sending env LC_MEASUREMENT = nl_NL.UTF-8
debug1: Sending env LC_TIME = nl_NL.UTF-8
debug1: Sending env LC_NAME = nl_NL.UTF-8
debug1: Sending subsystem: sftp
debug1: client_input_channel_req: channel 0 rtype exit-status reply 0
debug1: client_input_channel_req: channel 0 rtype [email protected] reply 0
debug1: channel 0: free: client-session, nchannels 1
debug1: fd 0 clearing O_NONBLOCK
Transferred: sent 4672, received 2772 bytes, in 0.6 seconds
Bytes per second: sent 7385.2, received 4381.8
debug1: Exit status 127
Connection closed

Ideally I could login with sftp with the main user account, so I could transfer files from my laptop to my server to whatever directory I wish and at the same time keep the 'sftpusers' group who are only able to login to /var/www/.

Does anyone know how I could do this? I appreciate your help very much! Btw, I am able to login to the server into the main user account using ssh.

Solution

Exit status 127 is command not found.

Your sshd_config shows: Subsystem sftp internal- sftp

The line is supposed to be Subsystem sftp internal-sftp (no space between internal and sftp) or else your sshd tries to execute it as an external command and fails.

Comments

[muru]

Ok, the server configuration seems fine. Try using verbose mode: sftp -v user@host -P ... (add more vs to get more detailed output).

[Parsijn]

I've added some of the results of verbose mode into the original question. And I'm looking into the Exit status 127 at the moment, but haven't found anything yet...

[Parsijn]

I totally forgot about his problem, but props for finding the solution. Thanks!