Quote Originally Posted by SCFg4gyODe View Post
At $JOB, our logs are getting swamped with messages saying:

"Too many concurrent connections, refusing"

It's hampering our ability to manage services, e.g.:

# systemctl status ntpd
Failed to get properties: Connection reset by peer

Near as I can tell from a quick read of the source of dbus.c, we're hitting a hard-coded limit of CONNECTIONS_MAX (set to 4096).

I think this is related to the number of connections systemd (pid 1) has to /run/systemd/private:

# ss -x | grep /run/systemd/private | wc -l
4015

But, despite the almost 4k connections, 'ss' shows that there are no connected peers:

# ss -x | grep /run/systemd/private | grep -v -e '* 0' | wc -l
0

- Are there any tunables that would help us mitigate the "Too many concurrent connections, refusing" messages?

- Is my guess about CONNECTIONS_MAX's relationship to /run/systemd/private correct?

I wanted to ask these questions directly to the systemd people, but their mail server is not configured to allow confirmation emails as to sign up to their mailing list:

<systemd-devel-request@lists.freedesktop.org>:
131.252.210.177 does not like recipient.
Remote host said: 550 5.1.1 <systemd-devel-request@lists.freedesktop.org>: Recip
ient address rejected: User unknown in local recipient table
Giving up on 131.252.210.177.
Hi and welcome to the Forum
Sounds like an issue with ntpd?

Code:
systemctl status ntpd

● ntpd.service - NTP Server Daemon
   Loaded: loaded (/usr/lib/systemd/system/ntpd.service; enabled; vendor preset: disabled)
  Drop-In: /run/systemd/generator/ntpd.service.d
           └─50-insserv.conf-$time.conf
   Active: active (running) since Sat 2019-06-29 16:28:56 CDT; 1 day 21h ago
     Docs: man:ntpd(1)
  Process: 19596 ExecStart=/usr/sbin/start-ntpd start (code=exited, status=0/SUCCESS)
 Main PID: 19605 (ntpd)
    Tasks: 2 (limit: 512)
   CGroup: /system.slice/ntpd.service
           ├─19605 /usr/sbin/ntpd -p /var/run/ntp/ntpd.pid -g -u ntp:ntp -c /etc/ntp.conf
           └─19606 ntpd: asynchronous dns resolver

Jun 29 16:28:56 gekkota-suma systemd[1]: Starting NTP Server Daemon...
Jun 29 16:28:56 gekkota-suma ntpd[19604]: ntpd 4.2.8p13@1.3847-o Wed Mar 13 12:24:30 UTC 2019 (1): Starting
Jun 29 16:28:56 gekkota-suma ntpd[19604]: Command line: /usr/sbin/ntpd -p /var/run/ntp/ntpd.pid -g -u ntp:ntp -c /etc/ntp.conf
Jun 29 16:28:56 gekkota-suma ntpd[19605]: proto: precision = 0.053 usec (-24)
Jun 29 16:28:56 gekkota-suma ntpd[19605]: basedate set to 2019-03-01
Jun 29 16:28:56 gekkota-suma ntpd[19605]: gps base set to 2019-03-03 (week 2043)
Jun 29 16:28:56 gekkota-suma ntpd[19605]: switching logging to file /var/log/ntp
Jun 29 16:28:56 gekkota-suma start-ntpd[19596]: Starting network time protocol daemon (NTPD)
Jun 29 16:28:56 gekkota-suma systemd[1]: Started NTP Server Daemon.

ntpq

ntpq> peers
     remote           refid      st t when poll reach   delay   offset  jitter
==============================================================================
*time-a-g.nist.g .NIST.           1 u  584 1024  205  168.297   -0.847   1.932
+time-b-g.nist.g .NIST.           1 u  289 1024    7  165.909   -0.151   0.442

gekkota-suma:~ # ss -x | grep /run/systemd/private | wc -l
0

systemctl status dbus
● dbus.service - D-Bus System Message Bus
   Loaded: loaded (/usr/lib/systemd/system/dbus.service; static; vendor preset: disabled)
   Active: active (running) since Sat 2019-06-29 15:16:13 CDT; 1 day 22h ago
     Docs: man:dbus-daemon(1)
 Main PID: 838 (dbus-daemon)
    Tasks: 1 (limit: 512)
   CGroup: /system.slice/dbus.service
           └─838 /bin/dbus-daemon --system --address=systemd: --nofork --nopidfile --systemd-activation

Jun 29 15:16:13 gekkota-suma systemd[1]: Started D-Bus System Message Bus.
Jun 29 15:16:15 gekkota-suma dbus[838]: [system] Activating via systemd: service name='org.freedesktop.hostname1' unit='dbus-org.freedesktop.hostname1.service'
Jun 29 15:16:15 gekkota-suma dbus[838]: [system] Successfully activated service 'org.freedesktop.hostname1'