Ubuntu

/usr/bin/sshd 在我的一個系統上沒有連結到 PAM。出了什麼問題,我該如何解決?

  • April 24, 2013

我使用 AD 作為我的 ldap 使用者帳戶伺服器。

大多數伺服器都使用 UsePam 執行,是的,除了這個,

它在 sshd 上缺乏 pam 支持。

root@linserv9:~# ldd /usr/sbin/sshd 
   linux-vdso.so.1 =>  (0x00007fff621fe000)
   libutil.so.1 => /lib/libutil.so.1 (0x00007fd759d0b000)
   libz.so.1 => /usr/lib/libz.so.1 (0x00007fd759af4000)
   libnsl.so.1 => /lib/libnsl.so.1 (0x00007fd7598db000)
   libcrypto.so.0.9.8 => /usr/lib/libcrypto.so.0.9.8 (0x00007fd75955b000)
   libcrypt.so.1 => /lib/libcrypt.so.1 (0x00007fd759323000)
   libc.so.6 => /lib/libc.so.6 (0x00007fd758fc1000)
   libdl.so.2 => /lib/libdl.so.2 (0x00007fd758dbd000)
   /lib64/ld-linux-x86-64.so.2 (0x00007fd759f0e000)

我安裝了這個包

root@linserv9:~# dpkg -l|grep -E 'pam|ssh'
ii  denyhosts                             2.6-2.1                      an utility to help sys admins thwart ssh hac
ii  libpam-modules                        0.99.7.1-5ubuntu6.1          Pluggable Authentication Modules for PAM
ii  libpam-runtime                        0.99.7.1-5ubuntu6.1          Runtime support for the PAM library
ii  libpam-ssh                            1.91.0-9.2                   enable SSO behavior for ssh and pam
ii  libpam0g                              0.99.7.1-5ubuntu6.1          Pluggable Authentication Modules library
ii  libpam0g-dev                          0.99.7.1-5ubuntu6.1          Development files for PAM
ii  openssh-blacklist                     0.1-1ubuntu0.8.04.1          list of blacklisted OpenSSH RSA and DSA keys
ii  openssh-client                        1:4.7p1-8ubuntu1.2           secure shell client, an rlogin/rsh/rcp repla
ii  openssh-server                        1:4.7p1-8ubuntu1.2           secure shell server, an rshd replacement
ii  quest-openssh                         5.2p1_q13-1                  Secure shell
root@linserv9:~# 

我做錯了什麼?

謝謝。

編輯:

root@linserv9:~# cat  /etc/pam.d/sshd 
# PAM configuration for the Secure Shell service

# Read environment variables from /etc/environment and
# /etc/security/pam_env.conf.
auth       required     pam_env.so # [1]
# In Debian 4.0 (etch), locale-related environment variables were moved to
# /etc/default/locale, so read that as well.
auth       required     pam_env.so envfile=/etc/default/locale

# Standard Un*x authentication.
@include common-auth

# Disallow non-root logins when /etc/nologin exists.
account    required     pam_nologin.so

# Uncomment and edit /etc/security/access.conf if you need to set complex
# access limits that are hard to express in sshd_config.
# account  required     pam_access.so

# Standard Un*x authorization.
@include common-account

# Standard Un*x session setup and teardown.
@include common-session

# Print the message of the day upon successful login.
session    optional     pam_motd.so # [1]

# Print the status of the user's mailbox upon successful login.
session    optional     pam_mail.so standard noenv # [1]

# Set up user limits from /etc/security/limits.conf.
session    required     pam_limits.so

# Set up SELinux capabilities (need modified pam)
# session  required     pam_selinux.so multiple

# Standard Un*x password updating.
@include common-password

Edit2:UsePAM 是失敗

使用此配置 ssh 無法啟動:

root@linserv9:/home/admmarc# cat /etc/ssh/sshd_config |grep -vE "^[ \t]*$|^#"
Port 22
Protocol 2
ListenAddress 0.0.0.0
RSAAuthentication yes
PubkeyAuthentication yes
AuthorizedKeysFile      .ssh/authorized_keys
ChallengeResponseAuthentication yes
UsePAM yes
Subsystem       sftp    /usr/lib/sftp-server
root@linserv9:/home/admmarc# 

它給出的錯誤如下

root@linserv9:/home/admmarc# /etc/init.d/ssh start
* Starting OpenBSD Secure Shell server sshd
/etc/ssh/sshd_config: line 75: Bad configuration option: UsePAM
/etc/ssh/sshd_config: terminating, 1 bad configuration options
  ...fail!
root@linserv9:/home/admmarc#

看起來您的/usr/sbin/sshd二進製文件已被覆蓋。

這可能意味著您遇到了安全漏洞,或者可能有人剛剛在本地編譯了一個版本,而 Ubuntu 版本被覆蓋了。

openssh-server的1:4.7p1-8ubuntu1.2(x86) 版本肯定與 libpam 相關聯。可以想像 pam 支持被排除在 64 位版本之外,但這似乎不太可能。

我會嘗試重新安裝 openssh-server:

# First back up the current binary
$ sudo cp /usr/sbin/sshd /root/sshd.bak

# reinstall the Ubuntu version
$ sudo apt-get install --reinstall openssh-server

# compare the two versions
$ sudo sha1sum /usr/sbin/sshd /root/sshd.bak

# In my case, they match:
# 8a3ccd5242380674bc45b887286faa3abb51acdb  /usr/sbin/sshd
# 8a3ccd5242380674bc45b887286faa3abb51acdb  /root/sshd.bak

如果你的不匹配(不是我的),肯定有一些可疑的事情發生,你真的需要弄清楚那個版本的sshd來源。

如果它們確實匹配,那麼我可能錯了,這是 64 位 Ubuntu 的該版本的 openssh-server 中的一個錯誤。

引用自:https://serverfault.com/questions/221155