这是我的sshd_config：

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

# What ports,IPs and protocols we listen for
Port 22
# 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
#Privilege Separation is turned on for security
UsePrivilegeSeparation yes

# Lifetime and size of ephemeral version 1 server key
KeyRegenerationInterval 3600
ServerKeyBits 768

# Logging
SyslogFacility AUTH
LogLevel INFO

# Authentication:
LoginGraceTime 120
PermitRootLogin no
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 yes

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

# GSSAPI options
GSSAPIAuthentication no
#GSSAPICleanupCredentials yes

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

#MaxStartups 10:30:60
Banner no

# Allow setting environment variables
AcceptEnv LANG LC_*

#Subsystem sftp /usr/lib/openssh/sftp-server
Subsystem sftp /usr/lib/openssh/sftp-server
UsePAM yes

AllowUsers user@xx.xxx.xx.xxx user@xx.xxx.xx.xxx apt-dater@xx.xxx.xx.xxx

Match User user
    PasswordAuthentication yes

我的连接尝试的详细输出：

me:~ user$sftp -v user@example.org
OpenSSH_6.9p1,LibreSSL 2.1.8
debug1: Reading configuration data /etc/ssh/ssh_config
debug1: /etc/ssh/ssh_config line 21: Applying options for *
debug1: Connecting to example.org [xx.xxx.xx.xx] port 22.
debug1: Connection established.
debug1: identity file /Users/user/.ssh/id_rsa type 1
debug1: key_load_public: No such file or directory
debug1: identity file /Users/user/.ssh/id_rsa-cert type -1
debug1: identity file /Users/user/.ssh/id_dsa type 1
debug1: key_load_public: No such file or directory
debug1: identity file /Users/user/.ssh/id_dsa-cert type -1
debug1: key_load_public: No such file or directory
debug1: identity file /Users/user/.ssh/id_ecdsa type -1
debug1: key_load_public: No such file or directory
debug1: identity file /Users/user/.ssh/id_ecdsa-cert type -1
debug1: key_load_public: No such file or directory
debug1: identity file /Users/user/.ssh/id_ed25519 type -1
debug1: key_load_public: No such file or directory
debug1: identity file /Users/user/.ssh/id_ed25519-cert type -1
debug1: Enabling compatibility mode for protocol 2.0
debug1: Local version string SSH-2.0-OpenSSH_6.9
debug1: Remote protocol version 2.0,remote software version OpenSSH_6.6.1
debug1: match: OpenSSH_6.6.1 pat OpenSSH_6.6.1* compat 0x04000000
debug1: Authenticating to example.org:22 as 'user'
debug1: SSH2_MSG_KEXINIT sent
debug1: SSH2_MSG_KEXINIT received
debug1: kex: server->client chacha20-poly1305@openssh.com <implicit> none
debug1: kex: client->server chacha20-poly1305@openssh.com <implicit> none
debug1: expecting SSH2_MSG_KEX_ECDH_REPLY
debug1: Server host key: ssh-rsa SHA256:/RUeBQCA1w0nHUWT2OgLDhy7/bNQy4nWH2IVZatMLw4
debug1: Host 'example.org' is known and matches the RSA host key.
debug1: Found key in /Users/user/.ssh/known_hosts:4
debug1: SSH2_MSG_NEWKEYS sent
debug1: expecting SSH2_MSG_NEWKEYS
debug1: SSH2_MSG_NEWKEYS received
debug1: SSH2_MSG_SERVICE_REQUEST sent
debug1: SSH2_MSG_SERVICE_ACCEPT received
debug1: Authentications that can continue: publickey,password
debug1: Next authentication method: publickey
debug1: Offering RSA public key: /Users/user/.ssh/id_rsa
debug1: Server accepts key: pkalg ssh-rsa blen 279
debug1: Authentication succeeded (publickey).
Authenticated to example.org ([xx.xxx.xx.xx]:22).
debug1: channel 0: new [client-session]
debug1: Requesting no-more-sessions@openssh.com
debug1: Entering interactive session.
debug1: Sending environment.
debug1: Sending env LANG = de_DE.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 eow@openssh.com reply 0
debug1: channel 0: free: client-session,nchannels 1
debug1: fd 0 clearing O_NONBLOCK
Transferred: sent 3332,received 2796 bytes,in 0.2 seconds
Bytes per second: sent 18890.9,received 15852.0
debug1: Exit status 127
Connection closed

知道怎么解决这个问题吗？