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目前，客戶只能在發(fā)現(xiàn)數(shù)據(jù)或者虛擬機(jī)被惡意侵入或者用戶的誤操作導(dǎo)致了數(shù)據(jù)的丟失之后，采取善后的手段，但是并沒法做到提前的預(yù)警。那么通過 PAM 模塊，就可以實(shí)現(xiàn)用戶登錄及獲取root 權(quán)限時(shí)，通過郵件的方式進(jìn)行通知。以實(shí)現(xiàn)預(yù)先知道、預(yù)先警惕的目標(biāo)，同時(shí)降低受影響的范圍。以下是通過 PAM 模塊實(shí)現(xiàn)的郵件通知用戶登錄的功能

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1.創(chuàng)建腳本（/tmp/ssh/login_notify.sh），備注：該腳本可存放在服務(wù)器的任意位置，但是需要將后續(xù)的路徑指定好

[root@hlmcen75n1-gen-um waagent]# cat /tmp/ssh/login_notify.sh 
#!/bin/bash

[ "$PAM_TYPE" = "open_session" ] || exit 0
{
echo "User: $PAM_USER"
echo "Ruser: $PAM_RUSER"
echo "Rhost: $PAM_RHOST"
echo "Service: $PAM_SERVICE"
echo "TTY: $PAM_TTY"
echo "Date: `date`"
echo "Server: `uname -a`"
} | mail -s "`hostname -s` $PAM_SERVICE login: $PAM_USER" user@yourdomain.com

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2.給腳本（/tmp/ssh/login_notify.sh）添加可執(zhí)行權(quán)限

[root@hlmcen75n1-gen-um ~]# chmod  x /tmp/ssh/login_notify.sh

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3.編輯文件(/etc/pam.d/sshd)，在文件最后追加一行(session optional pam_exec.so debug /bin/bash /tmp/ssh/login_notify.sh)

[root@hlmcen75n1-gen-um waagent]# cat /etc/pam.d/sshd 
#%PAM-1.0
auth       required    pam_sepermit.so
auth       substack     password-auth
auth       include      postlogin
# Used with polkit to reauthorize users in remote sessions
-auth      optional     pam_reauthorize.so prepare
account    required     pam_nologin.so
account    include      password-auth
password   include      password-auth
# pam_selinux.so close should be the first session rule
session    required     pam_selinux.so close
session    required     pam_loginuid.so
# pam_selinux.so open should only be followed by sessions to be executed in the user context
session    required     pam_selinux.so open env_params
session    required     pam_namespace.so
session    optional     pam_keyinit.so force revoke
session    include      password-auth
session    include      postlogin
# Used with polkit to reauthorize users in remote sessions
-session   optional     pam_reauthorize.so prepare
session optional pam_exec.so debug /bin/bash /tmp/ssh/login_notify.sh

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4.至此，每一個(gè)用戶登錄都會發(fā)郵件通知給收件人，內(nèi)容包括用戶名以及登錄的 IP 地址信息。如果遇到陌生 IP，那么就要注意。以此來判斷該虛擬機(jī)是否正在遭受攻擊，郵件示例如下：

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5.同理，你可以在把上述腳本應(yīng)用到 /etc/pam.d/ 其他模塊中，比如 sudo，login 等，來進(jìn)行監(jiān)控

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參考鏈接：https://docs./zh-cn/articles/azure-operations-guide/virtual-machines/linux/aog-virtual-machines-linux-security-reinforce

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