====== Troubleshooting ======

==== Packet Sniffing von der Kommandozeile: ====

  * [[http://networkingbodges.blogspot.de/2012/11/tshark-one-liners.html|Wireshark (tshark)]]
  * [[https://scrutin.wordpress.com/2007/04/06/quick-network-analysis-with-tcpdump/|Tcpdump Tutorial 1]]
  * [[https://danielmiessler.com/study/tcpdump/#gs.U9vx26M|Tcpdump Tutorial 2]]

==== IP und DNS Information ====
  * http://whatismyip.ch

=== DNSlytics ===
  * https://dnslytics.com/tools
  * https://dnslytics.com/ip/141.45.184.41


==== Traceroute ====
**Visual Traceroute**
  * http://www.monitis.com/traceroute/

**Traceroute mit Anzeige des Autonomen Systems (AS)**
<code bash>
traceroute -a www.spiegel.de
</code>

==== HTTP: ====

**HTTP über Telnet:**
<code http>
telnet www.spiegel.de 80

GET / HTTP/1.1
host: www.spiegel.de
</code>

  * [[http://www.esqsoft.com/examples/troubleshooting-http-using-telnet.htm]]
  * [[https://www.thomas-krenn.com/de/wiki/TCP_Port_80_(http)_Zugriff_mit_telnet_überprüfen]]

**HTTP über openssl:**
  * http://www.h-online.com/security/features/Testing-email-with-encryption-812464.html
==== Mail (SMTP): ====

**SMTP über Telnet:**
  * [[https://www.thomas-krenn.com/de/wiki/TCP_Port_25_(smtp)_Zugriff_mit_telnet_überprüfen]]
**SMTP über SSL:**
  * http://www.h-online.com/security/features/Testing-email-with-encryption-812464.html
==== UDP: ====

=== UDP-Pakete per Kommandozeile senden ===
<code bash>  
 echo -n "hello" >/dev/udp/localhost/8000 #may prefer IPv6!
 echo -n "hello" >/dev/udp/127.0.0.1/8000
</code>
  * https://help.ubidots.com/developer-guides/sending-tcpudp-packets-using-netcat
  * http://stackoverflow.com/questions/9696129/how-to-send-only-one-udp-packet-with-netcat

=== Herausfinden ob UDP-Ports offen sind ===
  * http://unix.stackexchange.com/questions/191655/using-bashs-dev-udp-how-would-i-know-if-the-port-was-open
==== NMAP: ====

https://www.cyberciti.biz/networking/nmap-command-examples-tutorials/
==== DNS: ====
http://dnscheck.iis.se/?faq=1&test=standard

==== SSH: ====

Falls SSH nicht funktioniert ist das meistens ein Problem falscher Permissions:
http://www.openssh.com/faq.html

<code bash>
chmod 700 $HOME/.ssh
chmod go-w $HOME $HOME/.ssh
chmod 600 $HOME/.ssh/authorized_keys
chown `whoami` $HOME/.ssh/authorized_keys
</code>

===== Verschiedenes =====

==== Herausfinden, welcher Prozess einen bestimmten Port benutzt ====

<code bash>
 netstat -vanp tcp | grep 443
 lsof -i tcp:443
 # anschließend mit ps das Programm ermitteln
 ps -p PID
</code>

----
==== Linux/Unix Layer-4-Ports ====
  * https://www.cyberciti.biz/faq/linux-unix-open-ports/

----

==== Telnet Escape-Character ====
**Mac**
<code bash>
 ctrl + ü
</code>

**Windows**
<code bash>
 ctrl + +
</code>  

  * http://superuser.com/questions/398/how-to-send-the-escape-character-on-os-x-terminal

----