VoovodeNET

Ressurecting a dead laptop - Dell XPS m1730

noreply@blogger.com (Alex Gkiouros) — Wed, 29 Oct 2014 19:46:00 +0000

There was a dell xps m1730 sitting besides me. Nobody had ever said something about it.
I decided to open the lid and check it. Everything ran smooth, i started reformatting, installed drivers and just after driver installating, bang! No video....

I didn`t know that it was a common m1730 problem up to the point i googled around a bit and found so many problems regarding GPU, even a video about reconstructing it on youtube.
I examined the laptop closely, unscrew everything and took it apart.
All i was able to notice was that the fans weren`t spinning at all...

Then, my friend google helped me find some posts inside dell's support area where i was able to find sources and details about the problem, what i found?
There was a bios update from dell support that looks promising into fixing the blank screen / vga problem. I downloaded into a usb stick, and booted from it to install the update.

Things weren`t so easy though, as soon as i got into (you know the blue area :) the flash rom, dell asked me to recharge the battery to continue! Battery? What battery? It was dead!

Questions... where can i find another battery? any alternative solution? Nope!
I decided it was time for debugging., then i found the assembly code of the function that checks battery charge.

What I changed in the MXG7A11.exe was the PUSH 3 to PUSH 0.

004213C0 /$ 55 PUSH EBP
004213C1 |. 8BEC MOV EBP,ESP
004213C3 |. 83EC 0C SUB ESP,0C
004213C6 |. 8D45 F4 LEA EAX,DWORD PTR SS:[EBP-C]
004213C9 |. 50 PUSH EAX
004213CA |. E8 FD0E0000 CALL
004213CF |. 807D F4 00 CMP BYTE PTR SS:[EBP-C],0
004213D3 |. 75 04 JNZ SHORT MXG7A11.004213D9
004213D5 |. 6A 01 PUSH 1
004213D7 |. EB 22 JMP SHORT MXG7A11.004213FB
004213D9 |> 807D F5 80 CMP BYTE PTR SS:[EBP-B],80
004213DD |. 74 1A JE SHORT MXG7A11.004213F9
004213DF |. 807D F5 FF CMP BYTE PTR SS:[EBP-B],0FF
004213E3 |. 74 14 JE SHORT MXG7A11.004213F9
004213E5 |. 807D F6 0A CMP BYTE PTR SS:[EBP-A],0A
004213E9 |. 76 0A JBE SHORT MXG7A11.004213F5
004213EB |. 807D F6 FF CMP BYTE PTR SS:[EBP-A],0FF
004213EF |. 74 04 JE SHORT MXG7A11.004213F5
004213F1 |. 33C0 XOR EAX,EAX
004213F3 |. C9 LEAVE
004213F4 |. C3 RETN
004213F5 |> 6A 03 PUSH 3
004213F7 |. EB 02 JMP SHORT MXG7A11.004213FB
004213F9 |> 6A 02 PUSH 2
004213FB |> 58 POP EAX
004213FC |. C9 LEAVE
004213FD \. C3 RETN

After this thing, the update worked like a charm ;)

CVE-2014-6271 - Shellshock

noreply@blogger.com (Alex Gkiouros) — Thu, 25 Sep 2014 13:46:00 +0000

A Critical remotely exploitable vulnerability has been discovered in the widely used Linux and Unix command-line shell, known as Bash, aka the GNU Bourne Again Shell, leaving countless websites, servers, PCs, OS X Macs, various home routers, and many more open to the cyber criminals.

REMOTELY EXPLOITABLE SHELLSHOCK

The vulnerability (CVE-2014-6271) affects versions 1.14 through 4.3 of GNU Bash and being named as Bash Bug, and Shellshock by the Security researchers on the Internet discussions.

According to the technical details, a hacker could exploit this bash bug to execute shell commands remotely on a target machine using specifically crafted variables. “In many common configurations, this vulnerability is exploitable over the network,” Stephane said.

This 22-year-old vulnerability stems from the way bash handles specially-formatted environment variables, namely exported shell functions. When assigning a function to a variable, trailing code in the function definition will be executed.

BASH BUG AFFECTS MILLIONS OF SYSTEMS

While bash is not directly used by remote users, but it is a common shell for evaluating and executing commands from other programs, such as web server or the mail server. So if an application calls the Bash shell command via web HTTP or a Common-Gateway Interface (CGI) in a way that allows a user to insert data, the web server could be hacked.

In Simple words, If Bash has been configured as the default system shell, an attacker could launch malicious code on the server just by sending a specially crafted malicious web request by setting headers in a web request, or by setting weird mime types. Proof-of-concept code for cgi-bin reverse shell has been posted on the Internet.

Similar attacks are possible via OpenSSH,
“We have also verified that this vulnerability is exposed in ssh—but only to authenticated sessions. Web applications like cgi-scripts may be vulnerable based on a number of factors; including calling other applications through a shell, or evaluating sections of code through a shell.”
Stephane warned. But if an attacker does not have an SSH account this exploit would not work.

This is a serious risk to Internet infrastructure, just like Heartbleed bug, because Linux not only runs the majority of the servers but also large number of embedded devices, including Mac OS X laptops and Android devices are also running the vulnerable version of bash Software. NIST vulnerability database has rated this vulnerability “10 out of 10” in terms of severity.

HOW TO CHECK FOR VULNERABLE SHELL

To determine if a Linux or Unix system is vulnerable, run the following command lines in your linux shell:

env X="() { :;} ; echo shellshock" /bin/sh -c "echo completed"

env X="() { :;} ; echo shellshock" `which bash` -c "echo completed"

If you see the words "shellshock" in the output, errrrr… then you are at risk.

BASH BUG PATCH

You are recommended to disable any CGI scripts that call on the shell, but it does not fully mitigate the vulnerability. Many of the major operating system and Linux distribution vendors have released the new bash software versions today, including:

Red Hat Enterprise Linux (versions 4 through 7) and the Fedora distribution
CentOS (versions 5 through 7)
Ubuntu 10.04 LTS, 12.04 LTS, and 14.04 LTS
Debian

If your system is vulnerable to bash bug, then you are highly recommended to upgrade your bash software package as soon as possible.

More here

Kali Linux - Assuring Security by Penetration Testing

noreply@blogger.com (Alex Gkiouros) — Wed, 23 Jul 2014 12:19:00 +0000

Interested about ‪#‎security‬? A big fan of ‪#‎kali‬ linux?Stay tuned with this amazing book from PacktPub.http://goo.gl/TQ80h3

This is what i posted today on my social networks, all about a perfect book.

This is a book where i chose to be a reviewer.
Excellent content inside, have a look on Amazon or on the publisher's website, PacktPub.

Reverse Engineering - Hack Norton GoBack

noreply@blogger.com (Alex Gkiouros) — Wed, 19 Feb 2014 12:27:00 +0000

That was an old trick i used as a PoC to some of my fellas, some years ago in a net station : > This hack will definitely get you out of shit. Especially when you're in troubles!

1. Run OllyDbg, open file GBOption.exe in "%Program Files%\Norton GoBack".

2. Hit F9 in OllyDbg. The Norton GoBack Options will appear.
Choose 2nd tab, click "Change Level...". A window to change level for each action will appear: enable/disable, uninstall, autobackup... There are three levels: ADMIN, USER and NONE. By default, the level for uninstall is ADMIN, mean that you must have administrator password in order to uninstall it.

3. Return to OllyDbg, jump to address 0x0043697D by pressing Ctrl+G, enter address in it and click OK. Then you will notice these addresses below:

00436970 > 8B0D A8964700 MOV ECX,DWORD PTR DS:[4796A8]
00436976 . 50 PUSH EAX
00436977 . 51 PUSH ECX
00436978 . E8 93E9FFFF CALL GBOption.00435310
0043697D . 83C4 08 ADD ESP,8
00436980 . 85C0 TEST EAX,EAX
00436982 . 0F954424 0F SETNE BYTE PTR SS:[ESP+F]

The address which GoBack uses to check administrator password is 0x00436978. This function will always return false because we're missing the password... So we will set a breakpoint in address 0x0043697D to change its return value by pressing F2. Then the line will change red.

4. Enter any pass you want and return to Norton GoBack Options, click OK, it will ask for the administrator password, enter anything you want and press OK. Now, the control is changed to OllyDgb, it ran to address where I set breakpoint and paused. Look in the registers window of OllyDbg, you'll see EAX = 0x00000090. Double click to it, change EAX to 0x00000000 and press F9 to continue. Now you'll see that no warning message was shown.

Voila! Owned....

Keep users happy: Don`t call them users.

noreply@blogger.com (Alex Gkiouros) — Wed, 12 Feb 2014 20:42:00 +0000

Sysadmin blog A common complaint about IT staff is their lack of social skills. As in any industry that attracts a certain type of person, there's a high percentage of dark-room-dwelling people who can sometimes struggle to communicate. This is either through what they say or how they interact with others.

Not all IT people are like this of course, just as nurses are not all popping out of their skimpy outfits and pool cleaners don't universally have a mustache and manage to find themselves in many interesting and awkward situations.

There are some guidelines I can recommend based on many years of personal experience, as well as observing others.

Helpdesk 101: Never trust the user. When a user tells you something is happening, see it for yourself. Think of this situation as if they just watched a doctor perform brain surgery, then had to summarise what happened. They're going to make guesses and assumptions on the bits they don't understand. Once you see the issue for yourself, then start the troubleshooting. There is no point spending hours chasing a dragon to slay if the dragon turns out to be a funny-shaped rock. Ask to see that error message or recreate the issue.

Don't call them 'users': IT staff can often forget they're in a position of service. Nobody likes getting bad service; it doesn't matter if it's the 15-year-old at your local fast food restaurant or a rude doctor. This means respecting every person you deal with. "User" is a technical word and should not be used outside of technical circles - people want to feel like people. Generally I would recommend calling them "staff" for internal people, and "clients" for external people – a good guide is to use the same term as other departments with their communications.

Turn a "no" into an alternative solution: Everyone gets questions that should receive a negative answer, but when someone reaches out for help, that's the last thing they want to hear. "Can I plug in my personal laptop and use it at work?" usually comes under that category. The answer should be an alternative solution to their problem. Maybe they can do everything over the internet from that laptop, or they just need to get some files off, which could be done via USB storage.

Often people will ask for something they think is the best solution to their problem, which means more questions need to be asked to find out what they are actually trying to accomplish.

Good communication: Keep people updated. Let them know someone is working on their issue. Let everyone know of outages and resolutions by whatever notification method works the best. Check if people want more assistance, or to be left alone. Follow-ups should always be done; all users should be notified somehow that their issue or request has been addressed.

Adaptation: Some users want to know every intricate detail about their brand new laptop and how to use all the fancy new options. Others will want the laptop left on their desk without a word. Part of adaptation is reading people and asking the right questions, and the other half is leading them down the path that actually helps them more.

You can't hassle that person who wants to be left alone, but if there's one important nugget of information, you need to get that across somehow. Just wiping your hands clean and walking away won't help: if they don't know their password was reset, they'll just get angry and think you're useless at your job.

This might all sound like common sense to many, but it takes a lot of time to build up trust with your userbase, while only a few slip-ups can completely destroy it. You're there to assist the business, and that often doesn't align with an individual's particular request, but part of your job should be to keep both sides happy.

Source

Windows XP svchost bug - finally a fix

noreply@blogger.com (Alex Gkiouros) — Mon, 20 Jan 2014 13:08:00 +0000

For the past several months, we have been checking on a bug in Windows XP that has caused SVCHOST to push the CPU of a PC up to 100 percent usage for some users. Microsoft tried in November to fix the issue but was unsuccessful. However, the company pledged to continue to work on fixing the bug, which it stated was due to "Windows Update Agent processing long lists of superseded updates."

On Tuesday, Microsoft depreciated legacy security updates for Internet Explorer that had been replaced by more recent ones. We did this to improve customer experience, reducing the time Windows Update requires to check existing updates before installing new ones. This action was purely to improve update performance and does not affect customer security.

The update came less than three months before all software patches for Windows XP from Microsoft will end on April 8th, although the company will continue to provide antivirus signatures for the OS until July 2015.

Windows Server 2012 R2 & HP Proliant Microserver

noreply@blogger.com (Alex Gkiouros) — Tue, 24 Dec 2013 11:17:00 +0000

Windows Server 2012 R2 hangs on 'Getting devices ready 84%'
Fails to Complete the installation on HP MicroServer Gen7 (N36L, N40L & N54L)

The MicroServer N36, N40L and N54L all share the same embedded NC107i PCI Express gigabit NIC. The NC107i uses the Broadcom BCM5723 chip which doesn’t have an updated driver included with the Server 2012 R2 installation media. The lack of drivers will get you stuck at 84%...

The current workaround is to disable the on-board NIC and install another card.
Flash the custom BIOS to unlock the hidden BIOS screens
Install a supported NIC in the PCIe slot (Joe used the Intel EXPI9301CTBLK
Go into the BIOS and change the settings to match
Boot Settings -> Embedded NIC Port 1 Control – [Disabled]
Boot Settings -> Wake-On LAN – [Disabled]
Chipset -> Atheros AR8132M NIC – [Disabled]
After a reboot, Server 2012 R2 should install fine.

Fall back to R1 or...., here's a solution for you!

Download this driver and add it to the $WinPEDriver$ folder of your media installation kit.
Disable Embedded NIC Port 1 Control in BIOS
Install Windows Server 2012 R2
Add a Server name
Reboot into BIOS to Enable the NIC
This should get you working, have fun!

HP have documented this as a known issue and are currently working with Microsoft to resolve prior to the official release of R2.

Global Smartphone Sales

noreply@blogger.com (Alex Gkiouros) — Thu, 12 Dec 2013 18:51:00 +0000

CouponAudit infographic.

This Infographic is produced by Coupon Audit (provides Zappos coupon code) and VoovodeNET

ITProDevConnections 2013

noreply@blogger.com (Alex Gkiouros) — Fri, 06 Dec 2013 09:09:00 +0000

ITProDevConnections

It's time to attend a conference this weekend all about technology with my friend nick.

I`ll possibly stick to the networking & security area again as every year....

Hope it's gonna be good! See you on monday!

Administer samba shares via SWAT

noreply@blogger.com (Alex Gkiouros) — Thu, 05 Dec 2013 19:39:00 +0000

Is it hard for you to play with smb.conf and other stuff? Are you afraid of doing any mistakes?

Then you have to think about using swat, the samba web administration tool.

We will first install samba, cifs-utils, swat and xinted, all needed for our SWAT installation.

sudo apt-get install samba cifs-utils swat xinetd

Then we will go ahead and enable swat in our internet service deamon,

sudo update-inetd --enable 'swat'
sudo dpkg-reconfigure xinetd

after xinetd, we will create the swat service.

sudo cat > /etc/xinetd.d/swat <<-EOF
service swat
{
port = 901
socket_type = stream
wait = no
user = root
server = /usr/sbin/swat
log_on_failure += USERID
disable = no
}
EOF

SWAT needs to have access to the smb.conf file to edit it automatically. We will now give those permissions and restart the xinetd service:

sudo chmod g+w /etc/samba/smb.conf
sudo chgrp adm /etc/samba/smb.conf
sudo service xinetd restart

By now you should be able to login to the administration tool via http://localhost:901/
Start sharing!

How to generate entropy in few easy steps

noreply@blogger.com (Alex Gkiouros) — Thu, 05 Dec 2013 19:18:00 +0000

You will possibly need this for a PGP key.. So how to generate entropy through a secure shell connection in an easy way?

You don`t have to smash the keyboard or move the mouse and stuff...

Install haveged, a simple entropy deamon.

apt-get install haveged

then type in -w with your bits:

haveged -w 4096

Now you can re-start your PGP-key entropy gatherer in order to finish quickly, right after it's done, you might consider removing haveged as i did.

apt-get remove haveged

Easy eh?

Disable Automatic Private IP Addressing - APIPA

noreply@blogger.com (Alex Gkiouros) — Fri, 29 Nov 2013 13:34:00 +0000

APIPA is Enabled

APIPA sometimes is tricky, giving us IPs in a range of 169.254.0.1 to 169.254.255.254
When a DHCP server fails, APIPA gives you an IP address. The client then verify that it's address is unique on the network by using ARP queries. Whenever a DHCP server sends the DHCPOffer packet, the clients requests a dhcp lease, thus leaving the APIPA addressing.

The best way to solve this is by heading to the registry editor and change a DWORD value to zero.

HKLM\SYSTEM\CurrentControlSet\Services\Tcpip\Parameteres
IPAutoconfigurationEnabled: 0

Transmission deamon - 409: Conflict - Invalid session-id header

noreply@blogger.com (Alex Gkiouros) — Fri, 15 Nov 2013 17:02:00 +0000

How to solve?
Remove the default /web from your URL:

http://www.example.com/transmission/web

http://www.example.com/transmission

HRESULT 0xc8000222 when trying to install any version of .netFramework

noreply@blogger.com (Alex Gkiouros) — Thu, 14 Nov 2013 00:04:00 +0000

This will occur mostly on Windows 7, never happened on Windows 8: 'Installation Did Not Succeed' .NET Framework has not been installed because: HRESULT 0xc8000222

There is a common problem with windows update and the .netframework. We'll have to clean the SoftwareDistribution folder before we proceed.

Click Start and Run:

cmd

This will open the well known Command Prompt, then type:

net stop WuAuServ

This will stop the Windows Update service. Make sure you're the admin.
Click Start and Run again, this time type %windir% and press Enter.
Look for the SoftwareDistribution folder and rename it to SwDist.old.
Now go back to the Command Prompt and start the Windows Update.

net start WuAuServ

That was it. Re-run the netFramework and it should work.

Watch live tasks running on remote pc

noreply@blogger.com (Alex Gkiouros) — Fri, 08 Nov 2013 08:48:00 +0000

This will work only if you have pstools installed on both of computers.

@echo off
set /p comp=Type IP or HOSTNAME:
echo.
IF "%comp%"=="" GOTO Error
c:\pstools\pslist \\%comp% -s
echo.
pause
GOTO End
:Error
echo No IP inserted.
echo.
pause
:End

Save it as batch file and run it.

Image to disk and vice versa on unix

noreply@blogger.com (Alex Gkiouros) — Sat, 02 Nov 2013 20:40:00 +0000

Backup all your usb drivers or your disk drivers, or clone them using dd, the ultimate tool.
We will first list all our available disks, watching out not making any mistake.

fdisk -l

Then after the output, notice the /dev/sdA or /dev/hdA or /dev/sdB etc, take a note on what device you want to take backup from, then think about the location of it going, like a folder or in another device.
if stands for input file.
of stands for output file.
By issueing the following command, we will backup our second drive into ~/.

dd if=/dev/sdb of=~/test.img

To restore it, simply swap /dev/sdb with ~/test.img, so simple!
You can also change the block size by using the bs command, eg:

dd if=/dev/sdb of=~/test.img bs=512

Vodaphone USB Broadband on Linux

noreply@blogger.com (Alex Gkiouros) — Sat, 19 Oct 2013 12:18:00 +0000

What you will need:

Right after you install those files on your linux box, append these three lines in a terminal:

usb_modeswitch -WD -v 12d1 -p 1526 -n -M 555342437f0000000002000080000a11062000000000000100000000000000 -I -w 500

modprobe option

echo "12d1 14cf" > /sys/bus/usb-serial/drivers/option1/new_id

Open your network manager window, select Mobile Broadband, create a new connection and for connection settings leave them as default, just set the password to 1234.

Plug-in your Vodafone USB and that's it !
[Source]

Disable ICMP ping responces on your linux box

noreply@blogger.com (Alex Gkiouros) — Sun, 06 Oct 2013 14:48:00 +0000

Depends on the distribution you use you may be able to disable the ping responce in your box to add some complexity for the attackers or the 'bad guys'. In the video below i am going to show you how to append such configuration in your linux distro.

Disable ping reply

echo 1 > /proc/sys/net/ipv4/icmp_echo_ignore_all

Enable ping reply

echo 0 > /proc/sys/net/ipv4/icmp_echo_ignore_all

To make this permanent set the following into /etc/sysctl.conf

net.ipv4.icmp_echo_ignore_all = 1

ICMP Message Types

You can find more about ICMP here.

Tips on hardening an enterprise server system

noreply@blogger.com (Alex Gkiouros) — Fri, 04 Oct 2013 23:14:00 +0000

Hardening a system is the process of making it more secure from the default configuration; it is a very important for servers. Before some time, security wasn't a primary concern, but with all the viruses and attacks on servers today, administrators need to consider about everything.

Keep the system updated

The risk of not being up to date is huge in the world we live on. Hundreds of vulnerabilities are being discovered day by day by security experts you should be aware of. It doesn't matter if your anti-virus is special or your firewall is wicked sick, trust me, for a hacker it's not a big deal to write some bof and win.

Follow the updates regularly and don't miss a thing, patch every hole. In windows world you may use WSUS feature in your server to serve updates to your network clients, this will save bandwidth in the network and save you before some unwanted patching.

Minimize the threat

A server should be installed only for the exact needs, if you're dealing with a server which you obviously don`t know what goes in and out, you're finished. Only the required services and protocols should work fine, rest should be disabled or removed. If you're working on windows environment, make sure to use group policy and the security configuration wizard to help you.

Use DMZ,.. demilitarization zone is a network added prior to the internal 'protected' network for extra security.
Use Firewalls, play your game and create your own rules in order to win. Policy-based filtering, iptables etc.

This tool should help your windows computers.

Enable TCP SYN cookie protection on your linux server

noreply@blogger.com (Alex Gkiouros) — Thu, 03 Oct 2013 16:05:00 +0000

Normally when a client attempts to start a TCP connection to a server, the client and server exchange a series of messages which normally runs like this:

The client requests a connection by sending a SYN (synchronize) message to the server.
The server acknowledges this request by sending SYN-ACK back to the client.
The client responds with an ACK, and the connection is established.

This is called the TCP three-way handshake, and is the foundation for every connection established using the TCP protocol.

A SYN flood attack works by not responding to the server with the expected ACK code. The malicious client can either simply not send the expected ACK, or by spoofing the source IP address in the SYN, causing the server to send the SYN-ACK to a falsified IP address - which will not send an ACK because it "knows" that it never sent a SYN.

The server will wait for the acknowledgement for some time, as simple network congestion could also be the cause of the missing ACK, but in an attack increasingly large numbers of half-open connectionswill bind resources on the server until no new connections can be made, resulting in a denial of service to legitimate traffic. Some systems may also malfunction badly or even crash if other operating system functions are starved of resources in this way.

The protection should be enabled by default in many distros.

Commands used:

sysctl -n net.ipv4.tcp_syncookies
nano /etc/sysctl.conf
sysctl -p

VLANs vs Subnetting

noreply@blogger.com (Alex Gkiouros) — Fri, 27 Sep 2013 11:41:00 +0000

Subnet
is a range of IP addresses determined by part of an address (often called the network address) and a subnet mask (netmask). For example, if the netmask is 255.255.255.0 (or /24 for short), and the network address is 192.168.10.0, then that defines a range of IP addresses 192.168.10.0 through 192.168.10.255. Shorthand for writing that is 192.168.10.0/24, 255 is for the broadcast and 0 is for the network address.

VLAN
A good way to think of this is "switch partitioning." Let's say you have an 8 port switch that is VLAN-able. You can assign 4 ports to one VLAN (say VLAN 1) and 4 ports to another VLAN (say VLAN 2). VLAN 1 won't see any of VLAN 2's traffic and vice versa, logically, you now have two separate switches. Normally on a switch, if the switch hasn't seen a MAC address it will "flood" the traffic to all other ports. VLANs prevent this.

If two computers are going to talk using TCP/IP, then one of two conditions must be met:

They must belong to the same subnet. This means the network address must be the same and the netmask must be equal or smaller. So, a computer with an interface with an IP address of 192.168.10.4/24 can talk to a computer with an interface with an IP address of 192.168.10.8/24 with no issues, provided they are both connected to the same physical switch or VLAN. If the second computer's interface connected to that same physical switch or VLAN was 192.168.11.8/24, it would ignore the traffic (unless the interface was in promiscuous mode).

A router needs to exist between both computers that can forward traffic between subnets. Computer A and computer B need a route (or default gateway) to this router. Let's say a computer with an interface with an IP address of 192.168.10.4/24 wants to talk to a computer with an interface with an IP address of 192.168.20.4/24. Different subnets, so we must go through a router. Let's say there's a router with two interfaces (routers by definition have two interfaces), one on 192.168.10.254/24 and 192.168.20.254/24. If the route table or DHCP is setup correctly and both computer A and B can reach the router's interfaces on their respective subnets, then they can talk to each other indirectly via the router.

Forcing traffic to go through a router, even though it's not needed such as on our 8-port switch above, has security and performance benefits - it gives you an opportunity to filter traffic, an opportunity to optimally route traffic based on type, and routers do not forward broadcast traffic (unless unusually configured). VLANs are sometimes used as a "hack" to manage flows/visibility of IPv4 broadcast traffic.

VLANs are equivalent to switches. What comes in 1 port of a VLAN is replicated("flooded") to all other ports unless the VLAN has seen/learned the MAC address before, then it is directed to that port. There is no gateway to the VLAN proper. A "gateway" always means the IP address of a router.

For VLAN 1 to talk to VLAN 2, an interface in VLAN 1 must be connected to a router, an interface in VLAN 2 must be connected to a router, and that router must be configured to forward traffic between those subnets. In our 8 port example above, if we wanted to route traffic between those VLANs, we'd have to spend 1 port on each VLAN connecting to a router. Same with a switch.

When a computer gets its IP via DHCP, it also usually gets the "default gateway" from that same DHCP server. Someone has to configure the DHCP server correctly. Routing protocols such as RIP, IS-IS, OSPF, and BGP can also add routes. Of course you have the option of adding static routes.

I'm sure many high-end switches/hardware have a "VLAN router" "built-in" to them where spending an extra port within each VLAN connecting it to a physical router really isn't necessary if you want to route between VLANs in the same switch. This might be where the VLAN IP or "gateway" comes into play.

mesa-libgl and nvidia-libgl are in conflict error

noreply@blogger.com (Alex Gkiouros) — Fri, 02 Aug 2013 13:55:00 +0000

pacman -Syu

and..

mesa-libgl and nvidia-libgl are in conflict, Remove nvidia-libgl? [y/N]

The following commands will fix it quickly:

pacman -Syu --ignore mesa-libgl
pacman -Sc
pacman -Rs xf86-video-ati
pacman -Rs ati-dri
pacman -S nvidia
pacman -Syu

Basically you update ignoring the mesa-libgl, then purge the pkg cache, remove xf86-video-ati which is 32bit ( maybe vmware would need that at the first place ), also ati-dri, then synchronize the nvidia drivers and do a full update.

Cisco router - Reset config

noreply@blogger.com (Alex Gkiouros) — Mon, 29 Jul 2013 00:19:00 +0000

Start putty & connect to the communication's port with the default rates etc....

Restart the cisco router in order to break the boot sequence of the router by tapping the Break key.

breaking the boot sequence...

After you broke the boot sequence, issue the following command:

confreg 0x2142

"You must reset or power cycle for new config to take effect" is what you will face after the proper usage of the above command, reset by giving this:

reset

issuing the reset command...

Now, after some time it should start booting.. It will ask you if you`d like to start from scratch.. say yes/no depending what you actually want to config.

[...] ~config taking place

After the configuration, you have to exit the NVRAM ignorance mode by issuing the commands below:

config-reg 0x2102

Exit config# using Ctrl+C and then:

wr mem
reload

Hint: If you would like not to reset the router's configuration - altering the password only is done through the same way but answering no to the 'start from scratch' dialogue, then by saving the running configuration giving the copy start run command at that time. For more info reply below.

Installing a LAMP server

noreply@blogger.com (Alex Gkiouros) — Sun, 28 Jul 2013 22:19:00 +0000

LAMP is a combination of free, open source software. The acronym LAMP refers to the first letters of Linux (operating system), Apache HTTP Server, MySQL (database software), and PHP, Perl or Python, principal components to build a viable general purpose web server.

Install Linux:
just kidding...

Install Apache:

sudo apt-get install apache2

http://localhost/

Install PHP:

sudo apt-get install php5 libapache2-mod-php5

sudo /etc/init.d/apache2 restart

Install MySQL:

sudo apt-get install mysql-server

mysql -u root

mysql SET PASSWORD FOR 'root'@'localhost' = PASSWORD('P@$sw0rd');

sudo apt-get install libapache2-mod-auth-mysql php5-mysql phpmyadmin

gksudo gedit /etc/php5/apache2/php.ini

;extension=mysql.so to extension=mysql.so

sudo /etc/init.d/apache2 restart

RDC authentication bypass

noreply@blogger.com (Alex Gkiouros) — Fri, 19 Jul 2013 12:11:00 +0000

This is not a hack.

Open up a command prompt and type mstsc.exe.
Click on Options drop down menu to access advanced options about the connection.
Save the connection settings by clicking Save As..., somewhere in your desktop.
Right click this .rdp file now and open it using notepad
Find authentication level:i:2 and turn it into authentication level:i:0.
Add enablecredsspsupport:i:0 at the end of the text file.
Then, open the rdp file which we've just edited and connect to the remote computer.
If it asks you for a password, enter the password of your local user account.

done!