Sencer H.'s questions

The rule in UFW for SR.CSR.CS.RC IP is:

ufw allow from SR.CSR.CS.RC

As described in the rule, SR.CSR.CS.RC can access this server over any enabled port.

But, when UFW is up and running, some lines are appears in UFW log file about request from SR.CSR.CS.RC IP has been blocked.

[UFW BLOCK] IN=ens3 OUT= MAC=11:00:11:00:11:ff:00:11:11:bb:ee:00:00:00 SRC=SR.CSR.CS.RC DST=D.ST.DST.DST LEN=52 TOS=0x00 PREC=0x00 TTL=63 ID=xyxyxy DF PROTO=TCP SPT=SPTSP DPT=SPTDP WINDOW=501 RES=0x00 ACK FIN URGP=0

Why am I seeing those logs while SR.CSR.CS.RC IP has be full access? Is it possible to UFW considers requests from SR.CSR.CS.RC IP are DOS attacks?

Note: SR.CSR.CS.RC is IP in disguise

Is this entry related with this: UFW logs blocked request on open port, what am I missing?

I tried to build and install systemd script for red5-server on ubuntu 16.04 server.

I found the sample init.d script at https://gist.github.com/akarambir/a40163f163ae8b131be8 and downloaded

I named the script with red5.sh and added to /etc/init.d with file mode 755 and modified the path of the red5.sh script path for where the file is installed

#!/bin/sh -
#
# red5      red5 server initscript
#
# Author:   Karambir Singh Nain <[email protected]>
#
### BEGIN INIT INFO
# Provides:     red5
# Required-Start:   $remote_fs $syslog
# Required-Stop:    $remote_fs $syslog
# Default-Start:    2 3 4 5
# Default-Stop:     
# Short-Description:    red5 media server
### END INIT INFO

set -e

PATH=/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin
DESC="Red5 flash streaming server"
NAME=red5
#RED5_HOME=/usr/local/red5
RED5_HOME=/root/red5-server
DAEMON=$RED5_HOME/$NAME.sh
PIDFILE=/var/run/$NAME.pid
LOGFILE=/var/log/$NAME.log
SCRIPTNAME=/etc/init.d/$NAME.sh

# Gracefully exit if the package has been removed.
test -x $DAEMON || exit 0

# Read config file if it is present.
if [ -r /etc/default/$NAME ]
then
    . /etc/default/$NAME
fi

#
#   Function that starts the daemon/service.
#
d_start() {
    start-stop-daemon --start --pidfile $PIDFILE \
                --chdir $RED5_HOME --background --make-pidfile \
        --startas /bin/bash -- -c "exec $DAEMON > $LOGFILE 2>&1"
}

#
#   Function that stops the daemon/service.
#
d_stop() {
    start-stop-daemon --stop --quiet --pidfile $PIDFILE \
        --name java
        rm -f $PIDFILE 
}

case "$1" in
  start)
    echo -n "Starting $DESC: $NAME"
    d_start
    echo "."
    ;;
  stop)
    echo -n "Stopping $DESC: $NAME"
    d_stop
    echo "."
    ;;
  restart|force-reload)
    echo -n "Restarting $DESC: $NAME"
    d_stop
    sleep 1
    d_start
    echo "."
    ;;
  *)
    echo "Usage: $SCRIPTNAME {start|stop|restart|force-reload}" >&2
    exit 1
    ;;
esac

exit 0

And then I create red5.service file and added to /etc/systemd/system folder with file mode 755. Then I run systemctl reload-daemon and systemctl enable red5.service

[Unit]
Description=Red5

[Service]
Type=simple
ExecStart=/etc/init.d/red5.sh

[Install]
WantedBy=multi-user.target

Anyway, when I try to run service with systemctl start red5.service and check the status with systemctl status red5.service, I receive this error:

● red5.service - Red5
   Loaded: loaded (/etc/systemd/system/red5.service; enabled; vendor preset: enabled)
   Active: failed (Result: exit-code) since Wed 2017-02-01 14:36:07 CET; 4s ago
  Process: 5236 ExecStart=/etc/init.d/red5.sh (code=exited, status=1/FAILURE)
 Main PID: 5236 (code=exited, status=1/FAILURE)

Feb 01 14:36:07 Ubuntu-1604-xenial-64-minimal systemd[1]: Started Red5.
Feb 01 14:36:07 Ubuntu-1604-xenial-64-minimal red5.sh[5236]: Usage: /etc/init.d/red5.sh {start|stop|restart|force-reload}
Feb 01 14:36:07 Ubuntu-1604-xenial-64-minimal systemd[1]: red5.service: Main process exited, code=exited, status=1/FAILURE
Feb 01 14:36:07 Ubuntu-1604-xenial-64-minimal systemd[1]: red5.service: Unit entered failed state.
Feb 01 14:36:07 Ubuntu-1604-xenial-64-minimal systemd[1]: red5.service: Failed with result 'exit-code'.

But when I try to run init.d script with sh /etc/init.d/red5.sh start commend, it's successfully started.

Am I missing something??

My company decided to upgrade the current MySQL NDB Cluster and reduce node size for increasing . The buy new Cluster machine with 4 nodes. Current cluster has 6 nodes. For make test on new cluster they suggest reprogram the current client scripts for sending same queries to both two clusters. There hundreds of client script we have to modify for doing this.

Eventually we will move all DB to new 4 node cluster and going to drop using current 6 node cluster.

Actually I'm not looking for replication. I just want to write one processed data into both cluster at once. Clusters are has different node size which is makes replication impossible. Also there are no data available in the new cluster yet, and they don't want to clone data to new cluster until stress testing with new cluster is done.

Once I research about MySQL Proxy but I think replication is necessary according to examples on the internet.

What is the most proper way to write a data to both two cluster?

I recently discovered selinux is disabled, but config file saying selinux enforcing mode setted. I read about possibilities about why selinux is disabled. I am suspecting on kernel. But I can't find what should I do to solve this problem. I'm afraid to touch anything because of the system is running remotely. My connection between system an me is only secure shell. There are a few continents between server and me. So, I need to solve this problem without make server unreachable :) What steps should I follow?

Information about server:

Centos 6.5
Linux 2.6.32-042stab068.8 #1 SMP Fri Dec 7 17:06:14 MSK 2012 i686 i686 i386 GNU/Linux

Server is running on VPS and so weirdly configured. I don't even detect which boot loader is installed on for check selinux configuration in boot loader.

Partitions (according to mtab):

/dev/simfs / simfs rw,relatime 0 0
proc /proc proc rw,relatime 0 0
sysfs /sys sysfs rw,relatime 0 0
none /dev devtmpfs rw,relatime,mode=755 0 0
none /dev/pts devpts rw,relatime,gid=5,mode=620,ptmxmode=000 0 0
none /dev/shm tmpfs rw,relatime 0 0
none /proc/sys/fs/binfmt_misc binfmt_misc rw,relatime 0 0

EDIT: Unfortunately, I've learned the kernel in server is not supporting Selinux. Because of it is specialized for OpenVZ.

I have Apache 2.2 running over CentOS 6.5 for first time. I faced no problem with Ubuntu with configurations below, but on CentOS always giving me 403 error. The example.com domain is living under Ubuntu server right now. If I can be able to run it under CentOS, I'll redirect example.com to CentOS server. But now I'm trying to run it with test.example.com domain. What am I doing wrong or missing?

Error that I faced:

[Mon Jun 23 15:30:40 2014] [error] [client ip] (13)Permission denied: access to / denied

Virtual Host conf:

NameVirtualHost ip:80
<VirtualHost ip:80>

    ServerName  example.com
    ServerAlias test.example.com

    <Directory /home/user/example>
        Order allow,deny
        Allow from all
    </Directory>

    WSGIDaemonProcess example user=user group=user python-path=/home/user/example:/home/user/example/venv/lib/python2.7/site-packages processes=2 threads=25 inactivity-timeout=60 maximum-requests=100
    WSGIProcessGroup example
    WSGIScriptAlias / /home/user/example/project/wsgi.py

    ErrorLog  /home/user/example/logs/error_log
    CustomLog /home/user/example/logs/access_log combined

    Alias /media/ /home/user/example/media/
    Alias /static/ /home/user/example/static/
</VirtualHost>

There are two servers I have. One is SQL server, other is Django project server. And sometimes I get too many unexpected EOF on client connection error by postgresql and OperationalError: could not connect to server: Connection timed out error by django project sametime. DB connection handled by Django itself. And I can't find out what is the problem. Does anybody has an opinion?

SQL server setup are as follows:

• 16 GB RAM
• i7-3770 CPU
• shmmax 8356163584
• PostgreSQL server 9.1 (Postgresql Config)
• Running on Ubuntu 12 64 bit Server LTS

Project server setup are as follows:

• 8 GB RAM
• i7-920 CPU
• Apache 2
• Django 1.3
• Python 2.6
• with pscopg2
• running on Ubuntu 10 64 bit Server LTS

With this setup I have some postgresql connection issues like below:

Postgresql.log :

2013-10-23 12:23:23 CEST LOG: SSL error: bad write retry 
2013-10-23 12:23:23 CEST LOG: could not send data to client: Connection reset by peer 
2013-10-23 12:23:23 CEST LOG: could not receive data from client: Connection reset by peer 
2013-10-23 12:23:23 CEST LOG: unexpected EOF on client connection 
2013-10-23 12:24:37 CEST LOG: could not send data to client: Broken pipe

Project Apache log Logged many of them per request:

[Wed Oct 23 12:22:36 2013] [error] Premature end of script headers: wsgi, referer: http://x.com/online/

Django Error mails dropped to my box per request:

OperationalError: could not connect to server: Connection timed out
        Is the server running on host "y.com" and accepting
        TCP/IP connections on port xxx?

mtr results for may gives any clue:

mtr -s 1500 -r -c 1000 -i 0.1 y.com
HOST: x.com                        Loss%   Snt   Last   Avg  Best  Wrst StDev
  1. static.xxx.xxx.x.188.clients  0.0%  1000    0.8   1.4   0.6   8.0   1.2
  2. hos-tr4.juniper2.rz10.hetzne  0.0%  1000    0.3   4.2   0.2 176.7  16.5
  3. core22.hetzner.de             0.0%  1000    0.4   0.4   0.3  25.3   1.5
  4. juniper4.rz16.hetzner.de      0.0%  1000    0.3   5.5   0.3 273.6  23.7
  5. hos-tr6.ex3k16.rz16.hetzner.  0.0%  1000    3.8   2.3   1.0  22.8   2.0
  6. y.com                         0.0%  1000    0.6   0.6   0.4  27.7   1.1

I've wrote a script for fetch real uptime and display in monit. But I think it displays just exit error status. My uptime script is:

#!/bin/sh
uptime=`uptime | awk -F " " '{print $3}'`
echo $uptime
exit $uptime

When I run it in terminal result is true

For example:

# uptime
 08:39:01 up 421 days, 19:54,  1 user,  load average: 0.06, 0.10, 0.06
# ./up_time.sh
421

Script works well. But when monit starts to run this script by up_time.conf file;

Program   Status     Last started                Exit value
days_up   Status ok  Thu, 01 Aug 2013 08:41:08      165

I saw on the browser. I guess that Exit value is the bash exit error code. I cant get why other script are works fine but this one does not do his job

Speaking of which, monit up_time.conf file is like this:

check program days_up with path "/etc/monit/scripts/up_time.sh"
    if status < 1 then alert

I need to find where GRUB was installed, for example, which drive/partition. Is it possible to figure out where it was installed?

I have remote Ubuntu 10.10 server running on raid system. I did package upgrade yesterday night for security reasons. During the upgrade, grub installation screen appeared and asked me which partition I wanted to install grub. Options are sda,sdb,md1 and md2. I decide to install them on both sda and sdb partitions.

I wondering, was I make true decision? If machine get reboot is it can be boot up safely?

You can find fdisk output and fstab mount points below:

Fstab:

proc /proc proc defaults 0 0
none /dev/pts devpts gid=5,mode=620 0 0
/dev/md0 none swap sw 0 0
/dev/md1 /boot ext3 defaults 0 0
/dev/md2 / ext3 defaults 0 0

Fdisk:

Disk /dev/sda: 750.2 GB, 750156374016 bytes
255 heads, 63 sectors/track, 91201 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x00029bb5

   Device Boot      Start         End      Blocks   Id  System
/dev/sda1               1         262     2102562   fd  Linux raid autodetect
/dev/sda2             263         295      265072+  fd  Linux raid autodetect
/dev/sda3             296       91201   730202445   fd  Linux raid autodetect

Disk /dev/md0: 2152 MB, 2152923136 bytes
2 heads, 4 sectors/track, 525616 cylinders
Units = cylinders of 8 * 512 = 4096 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x00000000

Disk /dev/md0 doesn't contain a valid partition table

Disk /dev/md1: 271 MB, 271319040 bytes
2 heads, 4 sectors/track, 66240 cylinders
Units = cylinders of 8 * 512 = 4096 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x00000000

Disk /dev/md1 doesn't contain a valid partition table

Disk /dev/md2: 747.7 GB, 747727224832 bytes
2 heads, 4 sectors/track, 182550592 cylinders
Units = cylinders of 8 * 512 = 4096 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x00000000

Disk /dev/md2 doesn't contain a valid partition table

Disk /dev/sdb: 750.2 GB, 750156374016 bytes
255 heads, 63 sectors/track, 91201 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x00088969

   Device Boot      Start         End      Blocks   Id  System
/dev/sdb1               1         262     2102562   fd  Linux raid autodetect
/dev/sdb2             263         295      265072+  fd  Linux raid autodetect
/dev/sdb3             296       91201   730202445   fd  Linux raid autodetect