Differences

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--- redhat:base-redhat:basics-redhat [2017/08/22 10:27] – michael
+++ redhat:base-redhat:basics-redhat [2019/05/27 16:27] – michael
@@ Line 1: / Line 1: @@
 ====== Grundlagen für Redhat / CentOS7 ======
+{{ :linux:linux_grundlagen.jpg?nolink&600 |}}
 ----
 ===== Basis Know-How Redhat Systems =====
+  * [[linux:user-and-groups|]]
+  * [[linux:dateirechte|]]
 <WRAP center box 100%>
 ==== System Aktualisieren / Warten ====
 ''Grundlegende Systemwartung, durch Installation, von aktuellen Paketen und Upgraden des Kernels.''
-  - <wrap em>Upgrade System and Packages:</wrap><code># yum -y update</code>
+<wrap em>Upgrade System and Packages:</wrap><code># yum update -y</code>
 </WRAP>
@@ Line 25: / Line 31: @@
 ==== motd - Message of the day====
 ''Eigene motd (Login-Nachricht), nach dem Aufbau einer neuen SSH-Verbindung anzeigen lassen:''
-Add description and serial number to motd:
 <code># echo '
-      hxxxxx
+ ##############################################################################
-      IT2 Debian Test Server (251xxxxx)
+ #                                                                            #
+ #                 This is the admin-server of Michael Reber.                 #
+ #                                                                            #
+ #                                ATTENTION:                                  #
+ #                                                                            #
+ #             Unauthorized access to this system is prohibited !             #
+ #                                                                            #
+ #    This system is actively monitored and all connections may be logged.    #
+ #         By accessing this system, you consent to this monitoring.          #
+ #                                                                            #
+ ##############################################################################
-      Debian Stable (i386) Linux
+' > /etc/motd</code>
+</WRAP>
-      IT2 ApplicationServices
+<WRAP center box 100%>
+==== Neuer User anlegen ====
+''Benutzer anlegen und setzen von Passwort.''
+<code># adduser michael
+# passwd michael</code>
-      "akunamatata -> no worries mate .."
+''<wrap em>Root Privilegien für User:</wrap>''
+''As root, run this command to add your new user to the wheel group (substitute the highlighted word with your new user):'' <code># usermod -aG wheel michael</code>
+''Now your user can run commands with super user privileges!''
+''<wrap em>Root Privilegien für User & without PW:</wrap>''
+<code># echo "michael ALL=NOPASSWD: ALL" > /etc/sudoers.d/michael</code>
-' > /etc/motd</code>
 </WRAP>
+<WRAP center box 100%>
+==== Die Grösse eines Ordners anzeigen ====
+''Zeigt die effektive Grösse - human readable und rekursiv über alle Files dar.''
+<code># du -hs foswiki/</code>
+<sxh plain; gutter: false;>4.6G    foswiki/</sxh>
+</WRAP>
+<WRAP center box 100%>
+==== SSH Login auf Server mit DNS oder User-Hash Problemen ====
+''Das normale Login auf einen Linux Server via SSH:''
+<code># ssh vrh7f</code>
+<sxh plain; gutter: false;>
+@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
+@       WARNING: POSSIBLE DNS SPOOFING DETECTED!          @
+@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
+The RSA host key for vb7gl9 has changed,
+and the key for the corresponding IP address 172.18.13.12
+is unknown. This could either mean that
+DNS SPOOFING is happening or the IP address for the host
+and its host key have changed at the same time.
+@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
+@    WARNING: REMOTE HOST IDENTIFICATION HAS CHANGED!     @
+@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
+IT IS POSSIBLE THAT SOMEONE IS DOING SOMETHING NASTY!
+Someone could be eavesdropping on you right now (man-in-the-middle attack)!
+It is also possible that a host key has just been changed.
+The fingerprint for the RSA key sent by the remote host is
+SHA256:o7win3mceJwnnehEyiVaOM6ePdiKOWivbtUMhxHVr58.
+Please contact your system administrator.
+Add correct host key in /home/rebermi/.ssh/known_hosts to get rid of this messag                                                                                 e.
+Offending RSA key in /etc/ssh/ssh_known_hosts:778
+RSA host key for vb7gl9 has changed and you have requested strict checking.
+Host key verification failed.</sxh>
+----
+''<wrap em>Trotz Error auf Server einloggen:</wrap>''
+<code># ssh -o stricthostkeychecking=no vrh7f</code>
+</WRAP>
 ----
@@ Line 46: / Line 114: @@
 ===== Systemverwaltung =====
 ''Wichtige Tools, zum konfigurieren, abändern der System Einstellungen.''
+<WRAP center box 100%>
+==== Wechseln der Zeitzone ====
+  - ''Die aktuelle System-Zeitzone'' (Timezone) kann man sehr einfach anschauen: <code># timedatectl</code>
+  - ''Wenn man nun auf eine neue Timezone zu wechseln möchte, macht es sinn, sich zuerst die verfügbaren Zeitzonen anzuzeigen lassen:'' <code># timedatectl list-timezones</code>
+  - Um nun die aktuelle Timezone (Zeitzone) zu wechseln, verwendet man set-timezone zusammen mit der gewünschten TIMEZONE. <wrap em>Beispiel für die Schweiz</wrap>: <code># timedatectl set-timezone Europe/Zurich</code>
+</WRAP>
@@ Line 64: / Line 144: @@
 <WRAP center box 100%>
 ==== Show Kernel Version and Architecture ====
-<code># uname -a</code>
+  - ''Display the current Kernel Version:''<code># uname -a</code><sxh plain; gutter: false;>
-<sxh plain; gutter: false;>
 Linux vstif2.pnet.ch 3.10.0-514.21.1.el7.x86_64 #1 SMP Sat Apr 22 02:41:35 EDT 2017 x86_64 x86_64 x86_64 GNU/Linux
 </sxh>
-<code># cat /etc/redhat-release</code>
+  - ''Show System Server Release Version:''<code># cat /etc/redhat-release</code><sxh plain; gutter: false;>
-<sxh plain; gutter: false;>
 Red Hat Enterprise Linux Server release 7.4 (Maipo)
 </sxh>
@@ Line 309: / Line 387: @@
 </sxh>
 </WRAP>
+----
+===== Redhat Dokumentation zum Thema =====
+<WRAP center round download 80%>
+''{{ :redhat:base-redhat:red_hat_enterprise_linux-7-system_administrators_guide-en-us.pdf |}}''
+</WRAP>