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Linux 9 - Working the Command Line

Apr 14, 2012 · 4 min read · configure commands linux info

Bash Shell environment PATH environment variables history completion commands The shell that a user uses is defines in /etc/passwd testuser:x:1001:1001:testuser user:/home/testuser:/bin/bash The settings for how bash behaves are stored in a couple different places /etc/profile# /etc/profile: system-wide .profile file …

Linux 7 - Debian Package Management

Mar 23, 2012 · 10 min read · linux debian info

dpkg dpkg-reconfigure APT apt-get, apt-cache configuration aptitude dpkg -i, –-install install packagename.deb -l, –-list list all of the packages or specified -L, -–listfiles show files that are installed by a package -P, --purge will remove the program and configurations -p, --print detailed information -r, --remove…

Linux 5 - The Boot Manager

Mar 18, 2012 · 2 min read · linux debian configure commands centos info

LILO GRUB BackUP the MBR LILO is rarely used the LILO configuration is stored in /etc/lilo.conf Explanation: –boot → what device it’s going to boot from (in this case the first serialATA –map → LILO creates a map file to say what is mapped where –install → default, leave this boot.b as the default –prompt → does it pr…

Linux 4 – Hard Disk Layout

Mar 15, 2012 · 2 min read · configure commands linux info

Partitons and Disk Filesystems mount points swap space design considerations Important folders in Linux/boot → (about 100MB+ is fine) for kernel, initrdcan not be read if software raid is present/home → user related folders & files, configuration files, etc/etc → configuration files, system wide/root → root’s home…

Linux 2 - Boot The System

Mar 11, 2012 · 2 min read · linux info

BIOS Bootloader Kernel dmesg /var/log/messages init BIOS Changing boot order BootloaderThere's two bootloaders that are used, LILO (Linux Loader), and GRUB (Grand Unified Boot Loader)Here’s GRUB: There are two entries in this debian release The second one will go into recovery mode (it will let you log in with root ac…

Linux 1 – Hardware Settings and Configuring Settings

Mar 10, 2012 · 3 min read · settings linux info

In order to have a better understanding of GNU Linux we would need to understand it’s ways of seeing the hardware devices attached to the system. Determine Settings: HAL, dbus, udev /sys, /proc, /dev lsmod, lsusb, lspci Configure Settings: Set device ID Kernel Modules Adding / Removing devices 1.1 HAL, dbus, udevHAL H…

Spanning Tree Design

Nov 20, 2011 · 2 min read · ccna 3 port-blocking configure cisco stp info

Optimizing STP topology. In the first topology an Access Layer switch is designated as a root bridge for the entire network. Choosing a good root bridge should be based on: Performance Redundancy Packets should travel from an access layer switch to a distribution layer switch to a core layer switch without the …

Optimizare topologie GNS3

Sep 3, 2011 · 5 min read · routes router links ccna 2 gns3 info

Eficientizarea proceselor de cautare in tabela de rutare. Avem acum toate rutele statice configurate pe routere. Sa presupunem acum ca intre R1 si R2 nu este o legatura seriala ci una Ethernet. Un pachet Ip ar trebuie sa fie encapsulat intr-un frame Ethernet cu o adresa MAC destinatie. Daca pachetul IP va trebui sa se…

Configurare topologie simpla GNS3 partea a 3-a

Sep 2, 2011 · 5 min read · routes ccna 2 gns3 routing protocol configure protocols cisco info

Obiective rutarea statica Configurare Vizualizare Depanare Odata puse ip-urile pe toate interfetele si pe toate PC-urile mai ramane configurat protocolul de rutare. Un router trebuie sa stie unde sa duca pachetele, acesta foloseste tabela de rutare, fara informatii actualizate acesta nu poate lua decizii corecte. Rout…

CDP

Sep 1, 2011 · 3 min read · ccna 2 gns3 configure basic cisco cdp commands info

Cisco Discovery Protocol - bun pentru obtinerea informatiilor de la alte routere sau swtich-uri direct conectate. - se trimit mesaje periodice (60s) - default pornit - contin informatii de genul: - tipul de device - interfetele cu care au legaturi - versiuni ale IOS - modelul device-ului Poate fi folosit ca un tool pe…

Network Security

Jul 10, 2011 · 6 min read · ccna 4 security SSH basic cisco commands info

Why is security important ? If the security of the network is compromised there could be seroious consequences such as: loss of privacy theft of information legal liabity As time went on, and attackers' methods and tools improved, attackers no longer required the same level of sophisticated knowledge. Common terms for…

Frame Relay

Jul 4, 2011 · 2 min read · ccna 4 protocols info

Definition Frame relay este un protocol de comunicare de inalta viteza pentru retele WAN. Beneficii: Latime de banda mai mare la un cost mai scazut Surplus de latime de banda pentru o perioada limitata (burst) Mai putin overhead Viteze intre 1,544 Mbps si 44,376 Mbps Functioneaza atat la layer fizic cat si la data lin…

Key Elements of 802.3/Ethernet Networks

Mar 23, 2011 · 13 min read · ccna 3 ethernet switchport info

CSMA/CD -Carrier Sense If a device detects a signal from another device, it waits for a specified amount of time before attempting to transmit. "listening before transmit" mode -Multi-access Using a shared medium to communicate -Collision Detection When a device is in listening mode, it can detect when a collision occ…

VTP Pruning, Etherchannel, Port Blocking, Storm Control

Mar 20, 2011 · 5 min read · port-blocking etherchannel vtp port security storm control info

VTP Pruning Etherchannel (Introducere) Lab Recapitulare (1 – 4) Port Blocking Storm Control C ii zice lui B: Sunt interesat in VLAN-urile 20 si 30 B tunde corespunzator VLAN-ul 10 catre C si atat B ii zice lui A: Am interes in VALN-ul 10 si 20 dar am pe alta interfata si VLAN-ul 30 deci am interes in VLAN-ul 10…

VTP

Mar 14, 2011 · 5 min read · ccna 3 vtp port security VLAN cisco info

VLAN Trunking Protocol 1) Lab anterior Cerinte: Configurare manuala interfete de tip trunk Configurare manuala interfete de tip access Port-Security Maximum 3 1 static 2 dynamic Violation Protect Toate VLAN-urile la fiecare switch VLAN-uri: VLAN Spatiu de adrese Adrese 10 10.0.0.0/24 C1 –.1 C7 –.7 …

Performante

Feb 17, 2011 · 2 min read · ccna 2 info

In functie de cerinte CISCO are mai multe serii Pentru Provider Core7200, 7600, GSR-12000, CSR-1, CSR-3 Pentru Provider Edge2800/2900, 3800/3900 Pentru nivelul Acces800/1800/1900 Se mai tin cont de: Interfete fiziceThroughputUpgradeabilitate O interfata de retea poate avea o latime de banda de 10Gbp/s. Este bin…

Frame/Packet Format

Feb 7, 2011 · 2 min read · basic info

IP Packet Internet Protocol (IP) Packet Format The Internet Protocol specified in RFC 791 defines the IP packet format. The IP packet header has specific fields that contain information about the packet and about the sending and receiving hosts. Below is a list of the fields in the IP header and a brief description fo…

OSPF

Feb 6, 2011 · 10 min read · ccna 2 routing protocol configure basic ospf commands info

Open Shortest Path First protocol de rutare link state direct competitor pentru EIGRP (proprietar CISCO) Protocol de rutare classless Scalabil prin folosirea de zone Metrica valoare arbitrara denumita cost CISCO IOS foloseste bandwidth administrativ in calculul metricii Avantaje Convergenta mai rapida decat RIP (excep…

Routing Table

Jan 16, 2011 · 3 min read · routes rib ccna 2 cisco info

Principles 1. Every router makes its decision alone, based on the information it has in its own routing table. 2. The fact that one router has certain information in its routing table does not mean that other routers have the same information. 3. Routing information about a path from one network to another does not pr…