sftp的服务在sshd_config中配置，具体目录为/etc/ssh/sshd_config
一般情况下使用的是sftp-server。由BSD系统管理器提供sftp-server的命令如下：

  1. NAME
  2.      sftp-server -- SFTP server subsystem
  4. SYNOPSIS
  5.      sftp-server [-ehR] [-d start_directory] [-f log_facility] [-l log_level]
  6.                  [-P blacklisted_requests] [-p whitelisted_requests]
  7.                  [-u umask]
  8.      sftp-server -Q protocol_feature
  10. DESCRIPTION
  11.      sftp-server is a program that speaks the server side of SFTP protocol to
  12.      stdout and expects client requests from stdin.  sftp-server is not
  13.      intended to be called directly, but from sshd(8) using the Subsystem
  14.      option.
  16.      Command-line flags to sftp-server should be specified in the Subsystem
  17.      declaration.  See sshd_config(5) for more information.
  19.      Valid options are:
  21.      -d start_directory
  22.              specifies an alternate starting directory for users.  The path-
  23.              name may contain the following tokens that are expanded at run-
  24.              time: %% is replaced by a literal '%', %d is replaced by the home
  25.              directory of the user being authenticated, and %u is replaced by
  26.              the username of that user.  The default is to use the user's home
  27.              directory.  This option is useful in conjunction with the
  28.              sshd_config(5) ChrootDirectory option.
  30.      -e      Causes sftp-server to print logging information to stderr instead
  31.              of syslog for debugging.
  33.      -f log_facility
  34.              Specifies the facility code that is used when logging messages
  35.              from sftp-server.  The possible values are: DAEMON, USER, AUTH,
  36.              LOCAL0, LOCAL1, LOCAL2, LOCAL3, LOCAL4, LOCAL5, LOCAL6, LOCAL7.
  37.              The default is AUTH.
  39.      -h      Displays sftp-server usage information.
  41.      -l log_level
  42.              Specifies which messages will be logged by sftp-server.  The pos-
  43.              sible values are: QUIET, FATAL, ERROR, INFO, VERBOSE, DEBUG,
  44.              DEBUG1, DEBUG2, and DEBUG3.  INFO and VERBOSE log transactions
  45.              that sftp-server performs on behalf of the client.  DEBUG and
  46.              DEBUG1 are equivalent.  DEBUG2 and DEBUG3 each specify higher
  47.              levels of debugging output.  The default is ERROR.
  49.      -P blacklisted_requests
  50.              Specify a comma-separated list of SFTP protocol requests that are
  51.              banned by the server.  sftp-server will reply to any blacklisted
  52.              request with a failure.  The -Q flag can be used to determine the
  53.              supported request types.  If both a blacklist and a whitelist are
  54.              specified, then the blacklist is applied before the whitelist.
  56.      -p whitelisted_requests
  57.              Specify a comma-separated list of SFTP protocol requests that are
  58.              permitted by the server.  All request types that are not on the
  59.              whitelist will be logged and replied to with a failure message.
  61.              Care must be taken when using this feature to ensure that
  62.              requests made implicitly by SFTP clients are permitted.
  64.      -Q protocol_feature
  65.              Query protocol features supported by sftp-server.  At present the
  66.              only feature that may be queried is ``requests'', which may be
  67.              used for black or whitelisting (flags -P and -p respectively).
  69.      -R      Places this instance of sftp-server into a read-only mode.
  70.              Attempts to open files for writing, as well as other operations
  71.              that change the state of the filesystem, will be denied.
  73.      -u umask
  74.              Sets an explicit umask(2) to be applied to newly-created files
  75.              and directories, instead of the user's default mask.
  77.      On some systems, sftp-server must be able to access /dev/log for logging
  78.      to work, and use of sftp-server in a chroot configuration therefore
  79.      requires that syslogd(8) establish a logging socket inside the chroot
  80.      directory.

修改ssh的配置

  1. vim /etc/ssh/sshd_config
  2. #搜索Subsystem找到对应的行
  3. # Subsystem sftp /usr/libexec/openssh/sftp-server
  4. # 在其后面增加日志配置参数
  5. Subsystem sftp /usr/libexec/openssh/sftp-server -l DEBUG3 -f local5

修改rsyslog的配置

由上诉的sftp-server的命令帮助中可知，在某些系统上，sftp-server必须能够访问/dev/log才能进行日志记录，因此在chroot配置中使用sftp-server需要syslogd(8)在chroot目录内建立日志记录套接字。

  1. vim /etc/rsyslog.conf
  2. # 在最后一行增加如下配置
  3. auth,authpriv.*,local5.* /var/log/sftp.log

重启服务

  1. systemctl restart sshd
  2. systemctl restart rsyslog

查看日志

  1. #日志最终会记录到/var/log/sftp.log中。可以使用tailf，less，more等命令进行查看
  2. tailf /var/log/sftp.log