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无法让并发 SFTP 用户登录

tag-icon • tag-icon networking server ssh sftp
无法让并发 SFTP 用户登录

我在 DMZ 中有一个 SFTP Ubuntu Server 16.04，如果一个用户通过 WINSCP 登录，另一个用户将无法登录。

SSHD 配置

欢迎使用 Ubuntu 16.04.3 LTS（GNU/Linux 4.4.0-112-generic x86_64）

# 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
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 VERBOSE

# 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 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 /usr/lib/openssh/sftp-server

# 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

如果需要，我可以发布更多信息，只是不确定从哪里开始，我认为这可能在用户或群组级别完成，但我不知道在哪里进行适当的更改。

编辑-尝试使用 WINSCP 连接时，我一次只能连接 1 个用户，无法连接多个用户，我确实将 maxstartup 500 添加到 sshd _config。我重新启动了服务，但问题仍然存在。如能得到任何帮助，我将不胜感激，谢谢

答案1

sshd_config 命令指定两个相关参数MaxSessions：MaxStartups

 MaxSessions
         Specifies the maximum number of open shell, login or subsystem
         (e.g. sftp) sessions permitted per network connection.  Multiple
         sessions may be established by clients that support connection
         multiplexing.  Setting MaxSessions to 1 will effectively disable
         session multiplexing, whereas setting it to 0 will prevent all
         shell, login and subsystem sessions while still permitting
         forwarding.  The default is 10.

 MaxStartups
         Specifies the maximum number of concurrent unauthenticated
         connections to the SSH daemon.  Additional connections will be
         dropped until authentication succeeds or the LoginGraceTime
         expires for a connection.  The default is 10:30:100.

         Alternatively, random early drop can be enabled by specifying the
         three colon separated values “start:rate:full” (e.g. "10:30:60").
         sshd(8) will refuse connection attempts with a probability of
         “rate/100” (30%) if there are currently “start” (10)
         unauthenticated connections.  The probability increases linearly
         and all connection attempts are refused if the number of
         unauthenticated connections reaches “full” (60).

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