我在Amazon EC2上托管了一个linux ubuntu服务器。在系统上创建了大约3000多个linux用户,userid为user_1,user_2&等等。
令人惊讶的是,用户直到user_2685才能通过ssh登录到服务器。不仅如此。
我已在/ etc / ssh / sshd_config中将LogLevel更改为DEBUG3。粘贴相关内容。
Apr 18 10:18:00 domU-12-31-39-01-86-0C sshd[18879]: debug1: Allocating pty. Apr 18 10:18:00 domU-12-31-39-01-86-0C sshd[18879]: debug3: mm_request_send entering: type 26 Apr 18 10:18:00 domU-12-31-39-01-86-0C sshd[18879]: debug3: mm_pty_allocate: waiting for MONITOR_ANS_PTY Apr 18 10:18:00 domU-12-31-39-01-86-0C sshd[18879]: debug3: mm_request_receive_expect entering: type 27 Apr 18 10:18:00 domU-12-31-39-01-86-0C sshd[18879]: debug3: mm_request_receive entering Apr 18 10:18:00 domU-12-31-39-01-86-0C sshd[18802]: debug3: mm_request_receive entering Apr 18 10:18:00 domU-12-31-39-01-86-0C sshd[18802]: debug3: monitor_read: checking request 26 Apr 18 10:18:00 domU-12-31-39-01-86-0C sshd[18802]: debug3: mm_answer_pty entering Apr 18 10:18:00 domU-12-31-39-01-86-0C sshd[18802]: debug2: session_new: allocate (allocated 0 max 10) Apr 18 10:18:00 domU-12-31-39-01-86-0C sshd[18802]: debug3: session_unused: session id 0 unused Apr 18 10:18:00 domU-12-31-39-01-86-0C sshd[18802]: debug1: session_new: session 0 Apr 18 10:18:00 domU-12-31-39-01-86-0C sshd[18802]: debug1: SELinux support disabled Apr 18 10:18:00 domU-12-31-39-01-86-0C sshd[18879]: debug1: do_cleanup Apr 18 10:18:00 domU-12-31-39-01-86-0C sshd[18879]: debug3: PAM: sshpam_thread_cleanup entering
Apr 18 10:20:07 domU-12-31-39-01-86-0C sshd[18957]: debug1: Allocating pty. Apr 18 10:20:07 domU-12-31-39-01-86-0C sshd[18957]: debug3: mm_request_send entering: type 26 Apr 18 10:20:07 domU-12-31-39-01-86-0C sshd[18957]: debug3: mm_pty_allocate: waiting for MONITOR_ANS_PTY Apr 18 10:20:07 domU-12-31-39-01-86-0C sshd[18957]: debug3: mm_request_receive_expect entering: type 27 Apr 18 10:20:07 domU-12-31-39-01-86-0C sshd[18957]: debug3: mm_request_receive entering Apr 18 10:20:07 domU-12-31-39-01-86-0C sshd[18880]: debug3: mm_request_receive entering Apr 18 10:20:07 domU-12-31-39-01-86-0C sshd[18880]: debug3: monitor_read: checking request 26 Apr 18 10:20:07 domU-12-31-39-01-86-0C sshd[18880]: debug3: mm_answer_pty entering Apr 18 10:20:07 domU-12-31-39-01-86-0C sshd[18880]: debug2: session_new: allocate (allocated 0 max 10) Apr 18 10:20:07 domU-12-31-39-01-86-0C sshd[18880]: debug3: session_unused: session id 0 unused Apr 18 10:20:07 domU-12-31-39-01-86-0C sshd[18880]: debug1: session_new: session 0 Apr 18 10:20:07 domU-12-31-39-01-86-0C sshd[18880]: debug1: SELinux support disabled Apr 18 10:20:07 domU-12-31-39-01-86-0C sshd[18880]: debug3: mm_request_send entering: type 27 Apr 18 10:20:07 domU-12-31-39-01-86-0C sshd[18880]: debug3: mm_answer_pty: tty /dev/pts/37 ptyfd 4 Apr 18 10:20:07 domU-12-31-39-01-86-0C sshd[18957]: debug1: session_pty_req: session 0 alloc /dev/pts/37 Apr 18 10:20:07 domU-12-31-39-01-86-0C sshd[18957]: debug1: Ignoring unsupported tty mode opcode 11 (0xb) Apr 18 10:20:07 domU-12-31-39-01-86-0C sshd[18957]: debug1: Ignoring unsupported tty mode opcode 17 (0x11) Apr 18 10:20:07 domU-12-31-39-01-86-0C sshd[18957]: debug1: server_input_channel_req: channel 0 request shell reply 1 Apr 18 10:20:07 domU-12-31-39-01-86-0C sshd[18957]: debug1: session_by_channel: session 0 channel 0 Apr 18 10:20:07 domU-12-31-39-01-86-0C sshd[18957]: debug1: session_input_channel_req: session 0 req shell Apr 18 10:20:07 domU-12-31-39-01-86-0C sshd[18957]: debug2: fd 3 setting TCP_NODELAY Apr 18 10:20:07 domU-12-31-39-01-86-0C sshd[18957]: debug2: channel 0: rfd 9 isatty Apr 18 10:20:07 domU-12-31-39-01-86-0C sshd[18957]: debug2: fd 9 setting O_NONBLOCK Apr 18 10:20:07 domU-12-31-39-01-86-0C sshd[18957]: debug3: fd 7 is O_NONBLOCK Apr 18 10:20:07 domU-12-31-39-01-86-0C sshd[18958]: debug1: Setting controlling tty using TIOCSCTTY. Apr 18 10:20:07 domU-12-31-39-01-86-0C sshd[18958]: debug3: Copy environment: PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games Apr 18 10:20:07 domU-12-31-39-01-86-0C sshd[18958]: debug3: Copy environment: LANG=en_US.UTF-8 Apr 18 10:20:07 domU-12-31-39-01-86-0C jk_chrootsh[18958]: now entering jail /opt/users-rails-apps for user user_1 (1001) with arguments
更新1:
上述转储来自服务器上的/var/log/auth.log。以下是客户端上的转储。只是将转储的相关部分放在不同的
成功登录
debug2: channel 0: request shell confirm 1 debug2: callback done debug2: channel 0: open confirm rwindow 0 rmax 32768 debug2: channel_input_status_confirm: type 99 id 0 debug2: PTY allocation request accepted on channel 0 debug2: channel 0: rcvd adjust 2097152 debug2: channel_input_status_confirm: type 99 id 0 debug2: shell request accepted on channel 0
登录失败
debug2: channel 0: request shell confirm 1 debug2: callback done debug2: channel 0: open confirm rwindow 0 rmax 32768 debug1: channel 0: free: client-session, nchannels 1 debug3: channel 0: status: The following connections are open: #0 client-session (t4 r0 i0/0 o0/0 fd 4/5 cc -1) Connection to www.codelearn.org closed by remote host. Connection to www.codelearn.org closed. Transferred: sent 2488, received 1472 bytes, in 0.8 seconds Bytes per second: sent 3043.4, received 1800.6 debug1: Exit status -1操作系统:Ubuntu精确到12.04
Openssh服务器:OpenSSH_5.9p1 Debian-5ubuntu1.1, OpenSSL 1.0.1 14 Mar 2012
SSH客户端:无所谓,因为我尝试过ubuntu以及Mac&行为是一样的。
更新2:
顺便说一句 - 这不是PAM的问题,因为我可以做su user_3000
&新用户登录&也得到了一个PTY。
在没有要求PTY ssh -T user_3000@www.codelearn.org
的情况下执行ssh也会记录用户。但是它会在登录后停止&没有提示出现。可能是因为第一时间没有要求提示。
答案 0 :(得分:0)
您是否检查过sshd_config
以确保没有发生最大问题?
了解
ClientAliveCountMax
MaxSessions
MaxStartups
特别是MaxSessions
,因为您的登录消息不成功会列出一堆打开的连接作为原因。增加数量并检查行为。
您可以在此处阅读更多内容 - http://www.manpagez.com/man/5/sshd_config/
答案 1 :(得分:0)
事实证明这对用户来说是/etc/security/limits.conf的问题。
我猜测PAM尝试通过查看/ etc / passwd文件作为用户进行身份验证。限制的字段fsize设置为1000。如果用户在/ etc / passwd中出现较早--PAM将能够找到&认证。如果他后来出现,可能已达到fsize limit& PAM退出。
将fsize从1000更改为2000解决了这个问题。