SSH登录通知发到Slack：用PAM和Webhook实现

Jared Lynskey — Tue, 14 Dec 2021 11:30:03 +0000

目的
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SSH可以在有人尝试登录时执行命令。这篇文章介绍怎么接入Slack，同时控制PAM的执行顺序。

Slack API的Webhook
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怎么创建应用，看这里就行。
你需要先建一个Slack应用，启用Webhook，再创建一个Incoming Webhook，用来接收SSH发来的通知。

登录失败的通知脚本
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脚本放在哪里都行，我放在了/var/opt/notify-attempt.sh。

#!/bin/bash
if [ "$PAM_TYPE" != "close_session" ]; then
        url=""
        channel="#channel"
        host="$(hostname)"
        content="\"attachments\": [ { \"mrkdwn_in\": [\"text\", \"fallback\"], \"fallback\": \"SSH login: $PAM_USER connected to \`$host\`\", \"text\": \"SSH login to \`$host\`\", \"fields\": [ { \"title\": \"User\", \"value\": \"$PAM_USER\", \"short\": true }, { \"title\": \"IP Address\", \"value\": \"$PAM_RHOST\", \"short\": true } ], \"color\": \"#F35A00\" } ]"
        curl -X POST --data-urlencode "payload={\"channel\": \"$channel\", \"mrkdwn\": true, \"username\": \"SSH Notifications\", $content, \"icon_emoji\": \":inbox-tray:\"}" "$url" &
fi
exit

其他SSH事件
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如果还想通知登录成功之类的事件，建议建两个文件。
每个文件里放好要发给Slack的JSON。
记得按事件改一下fallback\": \"SSH login: $PAM_USER connected to \$host`"`这一行。
OpenSSH怎么调用这些脚本，看下面的配置就明白了。

配置ssh
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登录成功的通知我注释掉了，想用的话取消注释，成功登录时也会发到Slack。就是这一行：# auth optional pam_exec.so /var/opt/notify-login.sh

[success=2]的意思是：登录成功就往下跳两行，正好跳过了失败通知。

文件：/etc/pam.d/common-auth

# /etc/pam.d/common-auth - authentication settings common to all services
#
# This file is included from other service-specific PAM config files,
# and should contain a list of the authentication modules that define
# the central authentication scheme for use on the system
# (e.g., /etc/shadow, LDAP, Kerberos, etc.). The default is to use the
# traditional Unix authentication mechanisms.
#
# As of pam 1.0.1-6, this file is managed by pam-auth-update by default.
# To take advantage of this, it is recommended that you configure any
# local modules either before or after the default block, and use
# pam-auth-update to manage selection of other modules. See
# pam-auth-update(8) for details.
# here are the per-package modules (the "Primary" block)
auth  [success=2 default=ignore]   pam_unix.so nullok
auth  optional            pam_exec.so /var/opt/notify-attempt.sh
# here's the fallback if no module succeeds
auth  requisite            pam_deny.so
# prime the stack with a positive return value if there isn't one already;
# this avoids us returning an error just because nothing sets a success code
# since the modules above will each just jump around
# For successful login, uncomment the below line, ensure the file exists.
# auth  optional            pam_exec.so /var/opt/notify-login.sh
# auth  required            pam_permit.so
# and here are more per-package modules (the "Additional" block)
auth  optional            pam_cap.so
# end of pam-auth-update config

谢谢！
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有任何问题或想法，欢迎直接联系我

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SSH登录通知发到Slack：用PAM和Webhook实现

目的 #

Slack API的Webhook #

登录失败的通知脚本 #

其他SSH事件 #