POFTUT – Page 101 – Linux, Windows, Security, Programming, Network Tutorials

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Linux KVM/Qemu Virt-Customize Tutorial

I am gonna show you today a practical and useful tool for managing Linux virtual machines and disks. Whit virtualization people start to use a lot of vms in their personal or corporate pc’s. But managing them is difficult. I faced with these difficulties too. So I search for a tool helps me especially in updates. I came with virt-customize which is a tool in libguestfs-tools package. Here we start. Load...

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How To Change Cisco IOS Time

Hi. Today we will look for changing system time and prompt.  You may think that what is the relation between system time and prompt, you are right there is no relation 🙂 . System time is important for network devices because logs get meaning with them and acl, vpn time limitations works truly with them. In order to change the system time we need enable mod not configure but I...

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Qemu Tutorial

Qemu is very old virtualization technology used to virtualize system components and run operating systems on it. Before KVM and XEN QEMU was used heavily but it can not race with VMWARE or VIRTUAL PC. But with the KVM qemu get superfast speed for computing by using hardware based virtualization. QEMU acts as a hardware supplier and KVM is the CPU. KVM resides in linux kernel and there is little...

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Linux Watch Command Tutorial With Examples

Some time generally long running operations like copying disk needs to track the change like disk usage or change of size of file. We generally run same command again and again but this is very cumbersome way yo see progress. Linux users created a “watch” application to make things better. When we use “watch” we can get change with specified interval times. Syntax We will use options with to change behavior...

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Bash Command Basics

Bash is a utility to manage Linux and UNIX boxes and it is very popular because of its simple, well documented and unique usage. There is alternatives to bash like csh,sh,ksh but bash has very high usage rate against others. I have recently work on bash with its manual and wanted to write something that I have learned from them. By the way bash is an acronym for “Bourne again...

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Tcpdump Tutorial With Examples

Tcpdump is packet sniffer for everyday use. There is lot of packet sniffers but tcpdump differs with his general availability and ease of use. Tcpdump use libcap library which is the core library used for packet sniffing. Here we will look general usage examples of packet sniffing. Be aware that to use tcpdump, tcpdump should have enough privilege and security mechanisms like selinux, apparmor should give permission. Captured data is...

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How To Create RSA Public and Private Key?

RSA is an algorithm used for Cryptography. It was patented until 2000 in USA (not whole world) where now it can be used freely. RSA has a lot of usage examples but it is mainly used for encryption of small pieces of data like key and Digital signatures. RSA is based integer factorization problem. As it is known that asymmetric ciphers are very slow against symmetric ciphers. So it is...

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How To Install and Use SNMP On Linux Tutorial with Examples?

Today we will look SNMP in Linux operating systems. Simple network management protocol named snmp is designed for getting info and setting configuration in it entities. These entities may be switch, router, pc, cabinet, printer etc. Snmp was very popular in 2000s. today it is popular too but used for information gathering. Especially monitoring which will be examined later is made today with snmp. Snmp has an index database which...

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Introduction To Scapy Network Packet Generator

Scapy is a tool for network protocol, package generation and manipulation and showing them in a visual way with graphics and 3D images. There are tools equivalent like hping3 but scapy is very flexible against it. Scapy can manipulate all data of general protocols like IP, Ethernet, tcp, udp etc. If you have a network protocol scenerio you can implement it with scapy and python scripting. I advise to read...

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How To Find External or Wan IP Address Without Browser?

Sometimes I need external IP address of system I am logged on. The general solution is to use browser and search for “what is my address” . And magically google shows the external IP. But if you have no chance to use browser or especially GUI there must be an alternative for this. Here is  a practical solution for this. Using text based browser with simple URL gives the correct...

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