各位朋友，
我创建了一个脚本，用于与 3G 调制解调器保持持久的“紧急”连接，这样如果常用网络出现故障，我就可以远程访问我的 CentOS 7 临时服务器。一切都正常了几秒钟，但随后某人使用 SIGTERM 终止 pppd：
Jul 08 17:03:29 helicarrier systemd[1]: Starting Network Manager Script Dispatcher Service...
Jul 08 17:03:29 helicarrier dbus-daemon[605]: dbus[605]: [system] Successfully activated service 'org.freedesktop.nm_dispatcher'
Jul 08 17:03:29 helicarrier dbus[605]: [system] Successfully activated service 'org.freedesktop.nm_dispatcher'
Jul 08 17:03:29 helicarrier systemd[1]: Started Network Manager Script Dispatcher Service.
Jul 08 17:03:29 helicarrier nm-dispatcher[12292]: Dispatching action 'up' for ppp0
Jul 08 17:03:29 helicarrier chronyd[616]: Source 146.164.48.5 online
Jul 08 17:03:29 helicarrier chronyd[616]: Source 5.9.110.236 online
Jul 08 17:03:29 helicarrier chronyd[616]: Source 192.99.2.8 online
Jul 08 17:03:29 helicarrier chronyd[616]: Source 200.192.232.8 online
Jul 08 17:03:53 helicarrier pppd[12279]: Terminating on signal 15
Jul 08 17:03:53 helicarrier pppd[12279]: Child process pppd (charshunt) (pid 12280) terminated with signal 15
Jul 08 17:03:53 helicarrier pppd[12279]: Modem hangup
Jul 08 17:03:53 helicarrier pppd[12279]: Connect time 0.4 minutes.
Jul 08 17:03:53 helicarrier pppd[12279]: Sent 4817 bytes, received 1170 bytes.
Jul 08 17:03:53 helicarrier pppd[12279]: Script /etc/ppp/ip-down started (pid 12323)
Jul 08 17:03:53 helicarrier pppd[12279]: Connection terminated.
Jul 08 17:03:53 helicarrier NetworkManager[702]: <info> (ppp0): device state change: activated -> unmanaged (reason 'removed') [100 10 36]
Jul 08 17:03:53 helicarrier NetworkManager[702]: <info> (ppp0): deactivating device (reason 'removed') [36]
Jul 08 17:03:53 helicarrier NetworkManager[702]: <info> NetworkManager state is now CONNECTED_LOCAL
Jul 08 17:03:53 helicarrier dbus-daemon[605]: dbus[605]: [system] Activating via systemd: service name='org.freedesktop.nm_dispatcher' unit='dbus-org.freedesktop.nm...er.service'
Jul 08 17:03:53 helicarrier dbus[605]: [system] Activating via systemd: service name='org.freedesktop.nm_dispatcher' unit='dbus-org.freedesktop.nm-dispatcher.service'
为了使内容更具可读性，这是相关行：
Jul 08 17:03:53 helicarrier pppd[12279]: Connection terminated.
我如何追踪发送此终止命令的程序？我主要怀疑是 NetworkManager，但我认为它不会干扰我的连接，因为我从未使用它进行连接（我使用我自己的旧式 pppd + 聊天脚本和一些技巧来保持连接始终开启）。