ubuntu – Why does systemd-resolve stop my java server?

I came across this problem where every few days one of my Java servers is dying. To find out why, I ran cat /var/log/syslog which produces:

Sep 21 06:36:24 ip-172-31-42-5 systemd-timesyncd(16235): Network configuration changed, trying to establish connection.
Sep 21 06:36:24 ip-172-31-42-5 systemd-timesyncd(16235): Synchronized to time server 91.189.91.157:123 (ntp.ubuntu.com).
Sep 21 06:46:45 ip-172-31-42-5 systemd(1): Starting Daily apt upgrade and clean activities...
Sep 21 06:47:35 ip-172-31-42-5 kernel: (5731409.370359) systemd-resolve invoked oom-killer: gfp_mask=0x14200ca(GFP_HIGHUSER_MOVABLE), nodemask=(null), order=0, oom_score_adj=0
...(skipping a bunch) ...
Sep 21 06:47:35 ip-172-31-42-5 kernel: (5731409.370580) Out of memory: Kill process 28251 (java) score 368 or sacrifice child
Sep 21 06:47:35 ip-172-31-42-5 kernel: (5731409.374244) Killed process 28251 (java) total-vm:2613628kB, anon-rss:178048kB, file-rss:0kB, shmem-rss:0kB
Sep 21 06:47:35 ip-172-31-42-5 kernel: (5731409.403233) oom_reaper: reaped process 28251 (java), now anon-rss:0kB, file-rss:0kB, shmem-rss:0kB

After reading this post, I learned that the oom_reaper stops the largest memory-intensive process when any process tries to allocate too much memory. Well, I suspect that systemd-resolve trying to request a ridiculous amount of memory, and then the reaper stops my bad java process.

I could handle that by putting it down vm.oom_kill_allocating_task As suggested in the link above, I'm trying to figure out why systemd-resolve is trying to request such an absurd amount of memory. Does anyone know what the basic problem is here?

Edit: When the Java server is running, memory usage is only 234M / 460M

Linux – MySQL does not work after using different commands. [Ubuntu 16.04]

I installed MySQL and MariaDB a few days ago and was able to use MariaDB to create a table of data in it. I think I forgot the password and I tried to uninstall MySQL and MariaDB from my computer. I've followed several different instructions for uninstalling and reinstalling, but the more I do, the more I break it. So I followed this special guide: here

I've gone through all the steps, and when I get to the installation step, I do the following:

sudo apt-get install mysql-server

Here is the output I get:

Building dependency tree       
Reading state information... Done
The following additional packages will be installed:
  libaio1 libevent-core-2.0-5 mysql-client-5.7 mysql-client-core-5.7
  mysql-common mysql-server-5.7 mysql-server-core-5.7
Suggested packages:
  mailx tinyca
The following NEW packages will be installed:
  libaio1 libevent-core-2.0-5 mysql-client-5.7 mysql-client-core-5.7
  mysql-common mysql-server mysql-server-5.7 mysql-server-core-5.7
0 upgraded, 8 newly installed, 0 to remove and 0 not upgraded.
Need to get 0 B/18.7 MB of archives.
After this operation, 161 MB of additional disk space will be used.
Do you want to continue? (Y/n) y
Preconfiguring packages ...
Selecting previously unselected package mysql-common.
(Reading database ... 437811 files and directories currently installed.)
Preparing to unpack .../mysql-common_1%3a10.3.18+maria~xenial_all.deb ...
Unpacking mysql-common (1:10.3.18+maria~xenial) ...
Selecting previously unselected package libaio1:amd64.
Preparing to unpack .../libaio1_0.3.110-2_amd64.deb ...
Unpacking libaio1:amd64 (0.3.110-2) ...
Selecting previously unselected package mysql-client-core-5.7.
Preparing to unpack .../mysql-client-core-5.7_5.7.27-0ubuntu0.16.04.1_amd64.deb ...
Unpacking mysql-client-core-5.7 (5.7.27-0ubuntu0.16.04.1) ...
Selecting previously unselected package mysql-client-5.7.
Preparing to unpack .../mysql-client-5.7_5.7.27-0ubuntu0.16.04.1_amd64.deb ...
Unpacking mysql-client-5.7 (5.7.27-0ubuntu0.16.04.1) ...
Selecting previously unselected package mysql-server-core-5.7.
Preparing to unpack .../mysql-server-core-5.7_5.7.27-0ubuntu0.16.04.1_amd64.deb ...
Unpacking mysql-server-core-5.7 (5.7.27-0ubuntu0.16.04.1) ...
Selecting previously unselected package libevent-core-2.0-5:amd64.
Preparing to unpack .../libevent-core-2.0-5_2.0.21-stable-2ubuntu0.16.04.1_amd64.deb ...
Unpacking libevent-core-2.0-5:amd64 (2.0.21-stable-2ubuntu0.16.04.1) ...
Processing triggers for libc-bin (2.23-0ubuntu11) ...
Processing triggers for man-db (2.7.5-1) ...
Setting up mysql-common (1:10.3.18+maria~xenial) ...
(Reading database ... 437973 files and directories currently installed.)
Preparing to unpack .../mysql-server-5.7_5.7.27-0ubuntu0.16.04.1_amd64.deb ...
Failed to stop mysql.service: Unit mysql.service not loaded.
invoke-rc.d: initscript mysql, action "stop" failed.
invoke-rc.d returned 5
There is a MySQL server running, but we failed in our attempts to stop it.
Stop it yourself and try again!
dpkg: error processing archive /var/cache/apt/archives/mysql-server-5.7_5.7.27-0ubuntu0.16.04.1_amd64.deb (--unpack):
 subprocess new pre-installation script returned error exit status 1
Selecting previously unselected package mysql-server.
Preparing to unpack .../mysql-server_5.7.27-0ubuntu0.16.04.1_all.deb ...
Unpacking mysql-server (5.7.27-0ubuntu0.16.04.1) ...
Errors were encountered while processing:
 /var/cache/apt/archives/mysql-server-5.7_5.7.27-0ubuntu0.16.04.1_amd64.deb
E: Sub-process /usr/bin/dpkg returned an error code (1)

The parts that annoy me again and again are the following:

There is a MySQL server running, but we failed in our attempts to stop it.
Stop it yourself and try again!

and

Errors were encountered while processing:
 /var/cache/apt/archives/mysql-server-5.7_5.7.27-0ubuntu0.16.04.1_amd64.deb
E: Sub-process /usr/bin/dpkg returned an error code (1)

I am not a Linux expert so I am very confused about what this could mean. I tried to go to mine etc/mysql Folder and delete all content inside, and still nothing worked.

When you execute this command:
mysqladmin -u root -p status
I get this output:

mysqladmin: connect to server at 'localhost' failed
error: 'Can't connect to local MySQL server through socket '/var/run/mysqld/mysqld.sock' (2)'
Check that mysqld is running and that the socket: '/var/run/mysqld/mysqld.sock' exists!

I also tried: sudo /etc/init.d/mysql stop
and got:

(....) Stopping mysql (via systemctl): mysql.serviceFailed to stop mysql.service: Unit mysql.service not loaded.
 failed!

Again, I can not read any of these errors. Usually I just copy and paste them, but some of the instructions talk about things I do not know. What's wrong with my MySQL installation?

ubuntu – Multiple interfaces and multiple users with Squid using NCSA Basic Authentication

Operating system: Ubuntu 18.04
Squid Version: 3.5.27
My squid proxy server currently has 3 interfaces. I'll call her
x.x.x.x
y.y.y.y
z.z.z.z
I want to have 3 users on my proxy server, each with its own IP address
For example, only user 1 may use the first IP address, user 2 may use the second, and user 3 may use the third. I looked for a solution and found that I could provide user NCSA authentication to authenticate users: Pass the authentication to the users so that all users can connect to one of the interfaces. Is there a way to achieve that only 1 user with a particular user can connect to 1 interface: pass. I have listed the important part of my configuration file as a reference below

acl ip1 localip x.x.x.x
acl ip2 localip y.y.y.y
acl ip3 localip z.z.z.z
tcp_outgoing_address x.x.x.x ip1
tcp_outgoing_address y.y.y.y ip2
tcp_outgoing_address z.z.z.z ip3

auth_param basic program /usr/lib/squid3/basic_ncsa_auth /etc/squid3/passwords
auth_param basic realm proxy
acl authenticated proxy_auth REQUIRED
http_access allow authenticated
http_access deny all

Networking – Ubuntu 18.04 sudo apt update gives a long list of connection timeout errors

I just installed Lubuntu 18.04.3 LTS and it works fine. I can connect to my wifi and surf the internet. In fact, I post here with it. However, if I try that sudo apt update it gives me some connection errors with timed out. Here is something of it.

Err: 1 http://security.ubuntu.com/ubuntu bionic-security InRelease
Failed to connect to security.ubuntu.com:80 (2001: 67c: 1360: 8001 :: 21).
– connect (101: Network is unreachable) Could not connect to security.ubuntu.com:80 (2001: 67c: 1562 :: 19). – connect (101: network is
unreachable) Could not connect to security.ubuntu.com:80
(2001: 67c: 1562 :: 16). – connect (101: network is unreachable) could not
Connect to security.ubuntu.com:80 (2001: 67c: 1560: 8001 :: 11). – connect
(101: Network is unreachable) Unable to connect
security.ubuntu.com:80 (2001: 67c: 1360: 8001 :: 17). – connect (101:
Network is unreachable) Could not connect to security.ubuntu.com:80
(2001: 67c: 1560: 8001 :: 14). – connect (101: network is not available)
Could not connect to security.ubuntu.com: 80 (91.189.91.14)

I'm trying to ping some of the IP, but it seems to work well. Here is the result

ping 91.189.88.174

PING 91.189.88.174 (91.189.88.174) 56 (84) Data bytes. 64 bytes
from 91,189,88,174: icmp_seq = 1 ttl = 54 time = 264 ms
— 91.189.88.174 ping statistics — 3 packets sent, 3 received, 0% packet loss, time 2002ms rtt min / avg / max / mdev =
264,493 / 264,750 / 265,008 / 0,210 ms

I am not sure where the problem lies. I hope I can get some help. Thank you for reading this long explanation

opengl – Kmscube under Ubuntu 16.04

I'm trying to run kmscube on Ubuntu 16.04.
I made it with meson and ninja, but I see this error when I try to do it:
i965_dri.so does not support the PCI ID 0xffffffff.
Using the ad 0x287e0f0 with EGL version 1.4

With the modifier ffffffffffffff
Modifiers failed!
Setting the mode failed: permission denied

glxinfo | grep "OpenGL version"
OpenGL Version String: 3.0 Mesa 18.0.5

What I miss
Thanks!

Networking – Wifi is disconnected after a Bluetooth device is connected to Ubuntu 18.04 LTS

I'm using Windows 8.1 along with Ubuntu 18.04 LTS on a Lenovo G50-70. Whenever I connect my JBL Bluetooth (v4.2) headset, my laptop's Wi-Fi connection will be disconnected after a few minutes. Everything works fine when I run Windows. So that's a problem with Ubuntu. Please, someone, help me with this problem.

I tried this command, echo "options iwlwifi 11n_disable=1 bt_coex_active=1 power_save=0 auto_agg=0 swcrypto=1" | sudo tee /etc/modprobe.d/iwlwifi.conf > /dev/null but that did not help.

I have executed lspci -knn | grep Net -A3to get my hardware information,

and here's the issue,

02:00.0 Network controller (0280): Realtek Semiconductor Co., Ltd. RTL8723BE PCIe Wireless Network Adapter (10ec:b723) Subsystem: Lenovo RTL8723BE PCIe Wireless Network Adapter (17aa:b736) Kernel driver in use: rtl8723be Kernel modules: rtl8723be 03:00.0 Display controller (0380): Advanced Micro Devices, Inc. (AMD/ATI) Sun LE (Radeon HD 8550M / R5 M230) (1002:666f) (rev ff)