Send mail via sendmail

vi /tmp/email.txt

Insert

Subject: Terminal Email Send
Email Content line 1
Email Content line 2

(ESC)wq(ENTER)

sendmail user@example.com < /tmp/email.txt

Quick and dirty, with subject only:

mail -s "Test Subject" user@example.com < /dev/null

Faking Mails with cutomized sender:

mail -s "Everything possible" -aFrom:bill.gargantur@iliketobeanemailfaker.com recipient@maildomain.com < /dev/null

*Will be delivered into spamfolder or not delivered cause SPF checks that mailsender is not authorized sender of the maildomain –> only if accurate spamsolution/SPF is implemented on recipient side

Install/Config sendmail
for just relay edit /etc/mail/sendmail.cf and add:

"Smart" relay host (may be null)

DSrelay.example.com

or if ip based:

"Smart" relay host (may be null)
DS[10.10.10.10]

of course relay host must permit this.

If you ever wanted an automation when a process is not running it is just a small script helping to achieve this:

check_process.sh (dont forget to make it executable)

check_process() {
  echo "$ts: checking $1"
  [ "$1" = "" ]  && return 0
  [ `pgrep -f $1` ] && return 1 || return 0 
#pgrep -n if process-name match exactly
}

while [ 1 ]; do
  # timestamp
  ts=`date +%T`
  echo "$ts: begin checking..."
  check_process "myprog.pl"
  [ $? -eq 0 ] && echo "$ts: not running, restarting..." && `/usr/bin/perl /home/me/myprog.pl >/dev/null`

sleep 10

done

You can also send yourself a mail instead of just starting process instead of

/usr/bin/perl /home/me/myprog.pl

do

echo "Subject: Process is stopped" | sendmail yourmail@mail.com

If you want to run this in background do

nohup check_process.sh &

or you can put this on startup via cronjob

crontab -e

@reboot root /home/me/check_process.sh

Origin/Source: https://stackoverflow.com/questions/7708715/check-if-program-is-running-with-bash-shell-script

If you have to find out who has mapped a network drive in Windows start a Command prompt and type

wmic netuse where LocalName="X:" get Username /value

replace „X:“ with the drive you want.

Lack of free space? just type in

du -sk *|sort -n

on /

or any folder you like. You will get an information about space occupation where you can investigate further.

Sample output:

0 fastboot
0 proc
0 sys
4 boot
4 dev
4 lib64
4 media
4 mnt
4 srv
8 aquota.user
8 home
12 aquota.group
16 lost+found
120 tmp
644 run
6080 bin
7244 sbin
8544 etc
29076 lib
1345892 opt
1364796 usr
3028736 root
12280360 var

yum help

yum list available

yum list installed

yum list all

yum list kernel

yum info vsftpd

yum deplist nfs-utils

yum provides “*bin/top”

yum search samba

yum updateinfo security

yum check-update

yum install --downloadonly vsftpd

yum install vsftpd

yum update httpd

yum update --security

yum autoremove httpd

yum remove vsftpd

yum downgrade abc

yum clean packages

show-installed

Experienced a memory leak on Windows Server 2011 Small Business Server. Tried to analyze with Process-Explorer and finally found out that the Windows SBS-Manager and the SQL-Database (SBSMonitoring) are the processes which consume more and more memory over the time. After some research i agreed with disabling the two services (https://serverfault.com/questions/522647/removing-sbs-monitoring-permanently-sbs-2008-2011)

I just read the news about IBM aquiring Red Hat

What will this will mean for CentOS?

Informix never forget 😉

Creation/Manipulation of tables:

CREATE TABLE tabelle (nummer int, text char(10), time datetime, date date);
DROP table tabelle;
ALTER TABLE table_name MODIFY (name char(100));
ALTER TABLE table_name ADD column_name column-definition;

can be positioned with AFTER/BEFORE

Unloading tables:

unload to '/home/content.csv'
delimiter ';'
SELECT * FROM content

Transactional Stuff:

BEGIN WORK;
ROLLBACK WORK;

Query Time:

SELECT |ALL|DISTINCT|UNIQUE|FIRST 
FROM table (WHERE)
GROUP BY columnname
HAVING COUNT(**)>1
ORDER BY columnname (ASC|DESC), ....
INTO TEMP tablename

WHERE-Clause:

bla (NOT) BETWEEN bla AND 
bla (NOT) IN (List, of, bla)
bla (NOT) LIKE "bla"
bla (NOT) EXISTS 
bla IS (NOT) NULL

to combine multiple selects

UNION

TO_CHAR transformation for query:

SELECT nr FROM numbers WHERE nr MATCHES "38*"
Error 219: Wildcard matching may not be used with non-character types.

SELECT nr FROM numbers WHERE TO_CHAR(nr) MATCHES "38*"

If you want to manipulate DNS-Entries before and without ISP-DNS Resolution you can do it with extra DNS-Server at your site. Best thing would be putting this DNS in DMZ-Zone.

e.g. Youre hosting WebEx and have one Public-URL to connect. Your Internal Clients will always route the traffic via Internet. To avoid this you can override the DNS – Resolving at your ISP with an own DNS. It’s also possible with your own Windows-DNS but… I like Linux 😉

Here I did with Linux, because its free:

Install BIND and configure named.conf

//
// named.conf
//
// Provided by Red Hat bind package to configure the ISC BIND named(8) DNS
// server as a caching only nameserver (as a localhost DNS resolver only).
//
// See /usr/share/doc/bind*/sample/ for example named configuration files.
//
 
options {
        listen-on port 53 { 127.0.0.1; 10.1.10.100; };
        listen-on-v6 port 53 { ::1; };
        directory       "/var/named";
        dump-file       "/var/named/data/cache_dump.db";
        statistics-file "/var/named/data/named_stats.txt";
        memstatistics-file "/var/named/data/named_mem_stats.txt";
        allow-query     { localhost; 10.1.0.0/16; 10.2.0.0/16; };
        recursion yes;
 
        //dnssec-enable yes;
        //dnssec-validation yes;
        //dnssec-lookaside auto;
 
        /* Path to ISC DLV key */
        //bindkeys-file "/etc/named.iscdlv.key";
 
        //managed-keys-directory "/var/named/dynamic";
 
        forwarders { 8.8.8.8; 8.8.4.4; };
 
};
 
logging {
        channel default_debug {
                file "data/named.run";
                severity dynamic;
        };
};
 
//zone "." IN {
//      type hint;
//      file "named.ca";
//};
 
 
include "/etc/named.rfc1912.zones";

Important parts of config:

Who is allowed to query this DNS?

 allow-query { localhost; 10.1.0.0/16; 10.2.0.0/16; };

Forward-Adresses for DNS-Requests which cannot be handled/resolved by the local DNS

forwarders { 8.8.8.8; 8.8.4.4; };

For your linking your own zones:

include "/etc/named.rfc1912.zones";

If you do changes, dont forget to restart

zone "override.untony.org" IN {
type master;
file "named.override.untony.org";
allow-update { none; };
};

$TTL 86400 @       IN SOA  @       root (                                         2013111501      ; serial                                         1D              ; refresh                                         1H              ; retry                                         1W              ; expire                                         3H )            ; minimum @        IN NS          localhost. @        IN A           194.232.104.3

MRemote NG is in my opinion the best tool for managing your Remote Connections!  (https://mremoteng.org)

Great tool to manage multiple SSH, Telnet, RDP, VNC, HTTP(S), etc