Understanding VPN IPSec Tunnel Mode and IPSec Transport Mode – What s the Difference? #ipsec, #modes, #tunnel, #transport, #esp, #ah, #encryption, #protocol, #security, #encapsulation, #decapsulation, #difference, #compare, #network, #gateway, #peer, #secure, #ip, #header, #protected, #unprotected


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Understanding VPN IPSec Tunnel Mode and IPSec Transport Mode – What’s the Difference?

IPSec’s protocol objective is to provide security services for IP packets such as encrypting sensitive data, authentication, protection against replay and data confidentiality.

As outlined in our IPSec protocol article. Encapsulating Security Payload (ESP) and Authentication Header (AH) are the two IPSec security protocols used to provide these security services. Analysing the ESP and AH protocols is out of this article’s scope, however you can turn to our IPSec article where you’ll find an in-depth analysis and packet diagrams to help make the concept clear.

Understanding IPSec Modes –Tunnel Mode Transport Mode

IPSec can be configured to operate in two different modes, Tunnel and Transport mode. Use of each mode depends on the requirements and implementation of IPSec.

IPSec Tunnel Mode

IPSec tunnel mode is the default mode. With tunnel mode, the entire original IP packet is protected by IPSec. This means IPSec wraps the original packet, encrypts it, adds a new IP header and sends it to the other side of the VPN tunnel (IPSec peer).

Tunnel mode is most commonly used between gateways (Cisco routers or ASA firewalls), or at an end-station to a gateway, the gateway acting as a proxy for the hosts behind it.

Tunnel mode is used to encrypt traffic between secure IPSec Gateways, for example two Cisco routers connected over the Internet via IPSec VPN. Configuration and setup of this topology is extensively covered in our Site-to-Site IPSec VPN article. In this example, each router acts as an IPSec Gateway for their LAN, providing secure connectivity to the remote network:

Another example of tunnel mode is an IPSec tunnel between a Cisco VPN Client and an IPSec Gateway (e.g ASA5510 or PIX Firewall). The client connects to the IPSec Gateway. Traffic from the client is encrypted, encapsulated inside a new IP packet and sent to the other end. Once decrypted by the firewall appliance, the client’s original IP packet is sent to the local network.

In tunnel mode, an IPSec header (AH or ESP header ) is inserted between the IP header and the upper layer protocol. Between AH and ESP, ESP is most commonly used in IPSec VPN Tunnel configuration.

The packet diagram below illustrates IPSec Tunnel mode with ESP header :

ESP is identified in the New IP header with an IP protocol ID of 50.

The packet diagram below illustrates IPSec Tunnel mode with AH header :

The AH can be applied alone or together with the ESP, when IPSec is in tunnel mode. AH’s job is to protect the entire packet. The AH does not protect all of the fields in the New IP Header because some change in transit, and the sender cannot predict how they might change. The AH protects everything that does not change in transit. AH is identified in the New IP header with an IP protocol ID of 51.

IPSec Transport Mode

IPSec Transport mode is used for end-to-end communications, for example, for communication between a client and a server or between a workstation and a gateway (if the gateway is being treated as a host). A good example would be an encrypted Telnet or Remote Desktop session from a workstation to a server.

Transport mode provides the protection of our data, also known as IP Payload, and consists of TCP/UDP header + Data, through an AH or ESP header. The payload is encapsulated by the IPSec headers and trailers. The original IP headers remain intact, except that the IP protocol field is changed to ESP (50) or AH (51), and the original protocol value is saved in the IPsec trailer to be restored when the packet is decrypted.

IPSec transport mode is usually used when another tunneling protocol (like GRE) is used to first encapsulate the IP data packet, then IPSec is used to protect the GRE tunnel packets. IPSec protects the GRE tunnel traffic in transport mode.

The packet diagram below illustrates IPSec Transport mode with ESP header :

Notice that the original IP Header is moved to the front. Placing the sender’s IP header at the front (with minor changes to the protocol ID), proves that transport mode does not provide protection or encryption to the original IP header and ESP is identified in the New IP header with an IP protocol ID of 50 .

The packet diagram below illustrates IPSec Transport mode with AH header :

The AH can be applied alone or together with the ESP when IPSec is in transport mode. AH’s job is to protect the entire packet, however, IPSec in transport mode does not create a new IP header in front of the packet but places a copy of the original with some minor changes to the protocol ID therefore not providing essential protection to the details contained in the IP header (Source IP, destination IP etc). AH is identified in the New IP header with an IP protocol ID of 51.

In both ESP and AH cases with IPSec Transport mode, the IP header is exposed.


Plasmid DNA Transfection Protocol #plasmid #transfection, #transfection #plasmid, #plasmid #transfection #protocol, #stable #transfection, #plasmid, #dna #transfection, #transfection #dna


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Это видео недоступно.

Plasmid DNA Transfection Protocol

Опубликовано: 7 авг. 2012 г.

How to perform Plasmid DNA transfection with Lipofectamine® LTX and Plus™ Reagent protocol. Superior plasmid delivery and protein expression.

In this video, we will perform a plasmid DNA transfection experiment using Lipofectamine® LTX & Plus™ reagent.

As always, use good cell culture practices and wear your personal protective equipment. Be sure to clean your cell culture hood and work surface by spraying and wiping them down with 70% ethanol.

The day prior to your transfection, seed your cells so that they will be 70% to 90% confluent at the time of your experiment.

For this transfection experiment you will need:
– Lipofectamine® LTX and Plus™ Reagent
– Opti-MEM® Reduced-Serum Medium
– Plasmid DNA at 1 microgram per microliter. We will be using a Green Fluorescent Protein plasmid to serve as a positive control for transfection.
– Five, 1.5 mL microcentrifuge tubes in a rack
– A P200 and P10 pipette and appropriate tips
– A marker and a timer
– And a 24-well plate with 70% to 90% confluent cells.

We will be following the 24-well plate format of the Lipofectamine® LTX & Plus™ Reagent protocol.

Prepare 4 tubes each with 50 microliter of Opti-MEM® Medium, and label them 1 to 4.

Add 2 microliters of Lipofectamine® LTX Reagent to tube 1, 3 microliters to tube 2, 4 microliters to tube 3 and 5 microliters to tube 4.

Mix each tube well by vortexing or flicking the tube.

Prepare a tube with 250 microliters of Opti-MEM® medium and add 5 micrograms of plasmid DNA. Since, our DNA concentration is at 1 microgram per mircoliter we are adding 5 microliters. Next add 5 microliters of Plus™ Reagent and mix well.

Add 50 microliters of the diluted DNA to each of the Lipofectamine® LTX dilutions in tubes 1 to 4.

Incubate the complex for 5 minutes at room temperature.

After the 5-minute incubation, remove your 24-well plate containing your cells from the incubator and bring it to the workspace in the hood.

Add 50 microliters of the DNA-reagent complex from tubes 1 to 4 to wells 1 to 4 of the 24-well plate, respectively.

You should have enough volume to run duplicates on the same plate if desired.

Place your 24-well plate back into the incubator and grow cells for 1 to 3 days at 37 Celsius.

After incubating your cells, assess the transfection efficiency in each well by viewing GFP fluorescence. Examine each well using a FLoid cell imaging station or microscope to determine which concentration of reagent provided the highest transfection efficiency.

In this experiment dilution 3 provided the highest transfection efficiency.

For transfection protocols, FAQ’s, troubleshooting and tips & tricks visit http://www.lifetechnologies.com/trans.

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IP Address Classes – IP Network Classes #ip #address, #ip #address #location, #ip, #tcp #ip, #tcp #ip #protocol #find #ip #address, #hide #ip, #my #ip #address, #my #ip, #ip #address #lookup, #proxy, #anonymous #proxy


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IP Network Classes


IP Networking Classes

Every host on a TCP/IP network needs to have a unique address, similar to you needing a unique address for your house. With this unique address, it is possible to send data from host to host.

Every packet contains addressing information in the header, and the IP address in the header is used to route packets.

If several people on your street had the same address, the post office would have a difficult time sorting mail. For a similar reason, IP addresses are unique on each network.

What is IP addressing?

IP addressing is simply configuring each TCP/IP host with a valid IP address.

For access to the Internet, a host must have an IP address that identifies not only the host address (like a house number) but also identifies the network address (like a street number).

An administrator needs to be aware of proper addressing techniques so that the hosts on the network will function correctly. TCP/IP addresses are based on 32-bit addresses.

IP Address classes

IP addresses are divided into five IP classes:
IP address class A
IP address class B
IP address class C
IP address class D
IP address class E

All IP addresses are placed in a particular class based on the decimal values of their first octets. In the first octet, an IP address can start with a decimal value between 1 and 255.

IP class A addresses have first octets with a decimal number from 1 to 127. Example:
27.x.y.z
102.x.y.z

IP class B addresses have first octets with a decimal number from 128 to 191.Example:
128.x.y.z
151.x.y.z

IP class C addresses have first octets with a decimal number from 192 to 223.Example:
192.x.y.z
223.x.y.z

IP class D addresses have decimal values from 224 to 239 in the first octet, and the 4 leftmost bits are 1110.Example:
224.x.y.z
239.x.y.z

The last IP address class of addresses is IP class E. IP class E addresses range from 240 to 255 in the first octet, and the 4 leftmost bits are 1111. Example:
240.x.y.z
255.x.y.z

The system of IP class addresses has been set up to help ensure assignment of unique IP addresses. DHCP discover, DHCP offer, DHCP request, and DHCP acknowledgment are are four steps in getting an IP address from a DHCP server.

Computer IP Address Configuration


To find out local what is My IP address and possible TCP/IP networking problem follow next steps:

  • If you use win9x/ME go to start-run and type winipcfg. and then press ENTER
  • For win2k/xp or wista go to start-run (Windows Wista user go to Windows button), type cmd and then ENTER. At the DOS prompt type ipconfig and you’ll see DNS suffix, IP address, subnet mask, and default gateway. For more info type ipconfig /all
  • For Macintosh select the TCP/IP control panel from the Apple menu’s “Control Panels” sub-menu. The TCP/IP control panel window will open and display your ip address.

SIP protocol #sip #protocol, #voip #providers #list, #voip, #provider, #list, #catalogue, #voice, #over, #ip, #voip #provider, #voip #providers, #itsp, #h.323, #sip, #ip #telephony #voip, #voice #over #ip,internet #telephony #service #provider, #internet #telephony, #telephony #provider, #voipproviders, #voip #provider


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SIP protocol

found 1139 companies

VoIP Provider. Diyanat
Location: India /Hyderabad
Main Category: Voip consulting
Categories: VoIP Billing Software Provider, SIP Billing, Voip consulting, Voip engineering
Protocols: SIP, IAX, h.323
Services: PC to Phone, IP devices, Installation and Support Services, H.323 VoIP Gateway, H.323 Softswitch & CPE, Gatekeepering, Consultancy Services, Billing Software, Phone To PC, Phone To Phone, SIP Softswitch & CPE, SIP VoIP Gateway, System Integration, Voice and Video Conferencing, Web To Phone

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VoIP Provider. Lantone Information Systems LLP
Location: Singapore
Main Category: Voip consulting
Categories: Voip consulting
Protocols: IAX, SIP
Services: Call Relay VoIP Solutions, Call Routing VoIP Solutions, Consultancy Services, IP devices, PC to Phone, Phone To PC, Phone To Phone, SIP VoIP Gateway, System Integration

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VoIP Provider. HablaporInternet
Location: Colombia /Bogota
Main Category: Hardware
Categories: Hardware, International VoIP Wholesale Provider, Voip consulting
Protocols: IAX, SIP
Services: Call Routing VoIP Solutions, Consultancy Services, H.323 Wireless/ GSM VoIP Solutions, IP devices, SIP VoIP Gateway, System Integration, Termination

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VoIP Provider. Switzernet
Location: Switzerland
Main Category: Internet Telephony Service Provider
Categories: International VoIP Wholesale Provider, Internet Telephony Service Provider
Protocols: SIP
Services: PC to Phone, Phone To PC

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VoIP Provider. Ntelecom – Your Next telecom
Location: Albania /Prishtine
Main Category: International VoIP Wholesale Provider
Categories: Hosted VoIP billing service provider, International VoIP Wholesale Provider, Internet Telephony Service Provider, Internet VoIP and Video Conferencing Service Provider, Network Service Provider, SIP Billing, VoIP Billing Software Provider, Voip consulting, Voip engineering, Voip Termination ISP
Protocols: h.323, SIP
Services: Billing Software, Call Relay VoIP Solutions, Call Routing VoIP Solutions, Collaboration, Consultancy Services, Data Conferencing, E1 Bulk Wholeseller, Fax To Fax, Gatekeepering, H.323 Softswitch & CPE, H.323 VoIP Gateway, H.323 Wireless/ GSM VoIP Solutions, Installation and Support Services, IP devices, Outsourced Billing, Partnering for Origination and Termination, PC to Phone, Phone To PC, Phone To Phone, Project Mangement Services, SIP Softswitch & CPE, SIP VoIP Gateway, System Integration, Termination, Voice and Video Conferencing, vPhone, Web Call, Web To Phone

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VoIP Provider. FAHR-TELECOM
Location: Germany /Frankfurt am Main
Main Category: Hardware
Categories: Hosted VoIP billing service provider, Hardware
Protocols: SIP, IAX
Services: Call Routing VoIP Solutions

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VoIP Provider. A-I.NetCom
Location: Italy
Main Category: International VoIP Wholesale Provider
Categories: Internet Telephony Service Provider, International VoIP Wholesale Provider, Network Service Provider, Voip Termination ISP
Protocols: h.323, SIP
Services: Call Routing VoIP Solutions, H.323 VoIP Gateway, H.323 Wireless/ GSM VoIP Solutions, SIP VoIP Gateway

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VoIP Provider. Airstar Communications Network
Location: Canada /Airdrie
Main Category: Hardware
Categories: International VoIP Wholesale Provider, Hardware
Protocols: h.323, SIP
Services: Termination

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VoIP Provider. Comcerto
Location: Bahrain /Manama
Main Category: VoIP Billing Software Provider
Categories: Voip consulting, VoIP Billing Software Provider, SIP Billing
Protocols: SIP, MGCP, IAX, h.323
Services: Installation and Support Services, Consultancy Services, Billing Software, SIP Softswitch & CPE

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VoIP Provider. SABA COMMUNICATIONS
Location: USA /BAKERSFIELD
Main Category: International VoIP Wholesale Provider
Categories: International VoIP Wholesale Provider
Protocols: SIP
Services: Call Routing VoIP Solutions

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What is VoIP caller ID (Voice over Internet Protocol caller identification)? Definition from #voice #over #internet #protocol


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VoIP caller ID (Voice over Internet Protocol caller identification)

VoIP caller ID (Voice over Internet Protocol caller identification) is a caller ID application for VoIP phone s that works in much the same way as caller ID on a conventional telephone line but with enhanced features and flexibility.

Download this free guide

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When a call comes in, the caller’s identity is verified by the Internet Service Provider (ISP ). Users can whitelist or blacklist specific telephone numbers or entities, just as is commonly done with e-mail. so unwanted calls do not reach the user.

This was last updated in March 2008

Related Terms

electret microphone An electret microphone is a widely-used electronic communications and audio recording device. The devices are a type of condenser. See complete definition microphone A microphone is a device that translates sound vibrations in the air into electronic signals or transmits them to a recording. See complete definition VoIP (voice over IP) VoIP enables voice and multimedia communications, such as phone calls, over the internet and other IP-based networks, and allows. See complete definition

Dig Deeper on VoIP QoS and Performance


Akamai Extends DDoS Protection With Prolexic Technology #akamai, #ddos, #distributed #denial #of #service, #prolexic, #web #security, #data #center #security, #network #timing #protocol


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Akamai Extends DDoS Protection With Prolexic Technology

VIDEO: Akamai s Chief Security Officer Andy Ellis explains how distributed denial-of-service (DDoS) protection is improving, even as the basic attack methods remain the same.

Akamai is well-known in the Web world for its capabilities as a content delivery network (CDN) provider. Akamai is also a leading vendor in the IT security space with distributed denial-of-service (DDoS) capabilities that have recently been expanded, thanks to the $370 million acquisition of data center DDoS vendor Prolexic.

In a video interview with eWEEK. Akamai Chief Security Officer Andy Ellis, explains how the Prolexic technology is now enhancing the DDoS mitigation capabilities at Akamai. Ellis also provides insight into the current generation of DDoS attacks, which surprisingly are not all that different from the DDoS attacks of 20 years ago.

Ellis explained that what Akamai was able to do before the Prolexic acquisition was focused around Website defense. Prolexic’s technology, in contrast, is about being able to protect data centers across multiple protocols. Akamai’s customers will now be able to benefit from the Prolexic operations model as well as Akamai’s network scale in defending against DDoS attacks.

While the volume of DDoS attacks is now growing, Ellis noted that, from a tactics perspective, some of the same techniques used 20 years ago by attackers are still in play in 2014.

Further reading

“20 years ago, we saw this myriad of reflection attacks,” Ellis said. “Where people would send UDP packets against one set of systems that would reflect back at a target to create a DDoS condition.”

In 2014, reflection attacks are once again in the news. In February 2014, one of the largest DDoS attacks ever reported hit the Internet and leveraged a Network Timing Protocol (NTP) reflection attack.

Ellis added,”Everything that is old is new again.”

While the total bandwidth used in DDoS attacks has grown as high as 400G bps according to cloud security vendor CloudFlare, Ellis doesn’t put much stock in the actual bandwidth figures.

“We don’t tend to look very carefully at networking-level traffic for precise measurement, partly because of the way our network is operated,” Ellis said. “It’s like trying to count the water that is lapping up against your seawall; you don’t worry about it until the water is high enough to come over the top of your seawall.”

Watch the full video interview with Andy Ellis, CSO at Akamai, below:

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