TTL is what?

TTL - what is it? TTL stands for Time to Live. That is, the lifetime of the packet assigned to it at the time of the transition from the initial node to the final node. In the standard IPv4, an eight-bit field in the header is allocated for TTL reflection. Passing through multiple nodes to the destination, the value of the packet is reduced by 1 unit each time. This is done in order to limit the time of its presence in the nodes by a specific number. And this, in turn, helps to avoid congestion in networks.

According to the idea of the authors of technology, the lifetime of the packet loses 1 unit every second. But due to the high connection speeds and the number of routers and nodes, the reduction occurs much faster.

What happens if TTL reaches zero? The package will disappear, and the sender will receive a message stating that his life time has expired, which means you need to try again. The maximum value that can reflect an eight-bit field is 255. For operating systems, there are default values. For example, TTL in Windows is 128, and in Linux and derivatives - Mac, Android - 64.

The DNS environment has its own TTL, and it reflects the relevance of the cached data. But speech in the article will not be about him.

Why TTL is used and in which areas

The lifetime of the package is actively used by various Internet providers, for example Yota. Thus they try to limit access to the consumption of excessive traffic when distributing Wi-Fi. This is due to the fact that the packet, moving from the device receiving traffic to the distributor, reduces TTL, as a result, the provider receives a value less or in the case of Windows more than expected.

For example, you can describe the process of the smartphone on the basis of "Android". The device sends a request for data from a specific site. Together with it, a TTL is sent, the value of which is 64. The provider knows that this is the standard time of the package for this device, therefore it allows it to freely access the Network.

Now the device begins to distribute Wi-Fi and becomes a kind of router. The connected smartphone runs on the Windows platform, and its TTL, passing through the distributing device, will be 127. The provider will meet this packet and understand that its Internet is being distributed. Therefore, it will block the connection.

TTL change capabilities on various devices

Changing the value of the packet's lifetime can be useful for circumventing traffic blocking by the provider. For example, if you disconnected the cable connection, and the user needs to immediately go online from the computer. Then the smartphone becomes an access point and outputs the PC to the network.

It is worth noting that some providers block access not only on TTL, but also track visits to sites. And if the resource is in no way connected with the smartphone, i.e., it is not needed to it, the connection terminates.

You can change TTL in several ways, which will be described later.

Change TTL on devices on the platform "Android"

The easiest way to change the lifetime of the package on Android devices will be the use of specialized software. For example, a very effective product - TTL Master. It can change the lifetime of the packet of the dispenser to the one that results from the data flow. For example, when you distribute Wi-Fi to a device with Windows, you need to set the value to 127, and to Android or Linux - to 63.

The program is free, and it can be easily found in the official Google Play store. However, its operation requires root rights on the device.

The program interface is simple - the current value of the parameter is displayed at the top. Slightly below are the blanks for Windows and other operating systems. You can also set the desired value manually. A little below there is a button with the ability to go from the application right into the modem settings. In some versions, a solution is available via iptables, for which there is a certain point.

In the settings, you can set the start and change the lifetime automatically when the device is booted. Some versions of "Android" can be produced immediately after changing the value of the launch of the access point. There is support for the Russian language.

The application is constantly evolving and improving. There is a profile on github, in which everyone can branch off and add their capabilities to the project. If they are accepted by the developers, they will be included in the subsequent release.

You can also try the method of changing system files manually to change the value of the lifetime of the package. To do this you need root-rights. First you need to switch to flight mode, that is, make the phone lose the Network.

Then use any explorer that is able to edit the files. In it, go to the proc / sys / net / ipv4 path. In this directory, a file called ip_default_ttl is of interest. It contains a value of 64, which must be changed to 63.

Next, you need to take the phone out of flight mode, so that it registers on the Web again. Now you can distribute the wireless Internet and try to connect the device based on iOS or "Android", that is, with TTL 64.

If you want to use as one of the Windows PC winches, you will need to set a constant value for the lifetime of the package in the manner described below.

Change TTL on a computer with Windows operating systems

If you need to distribute the Internet from the smartphone "Android" to a computer running Windows, you will have to adjust the registry values a little. This method will be relevant, when the phone does not have a root and bypass the lock on it does not work.

You can start the registry in the operating system line through the Start menu item Run. In it, you need to enter Regedit and click OK. In the window that opens, two areas will appear. The tree structure is on the left, and the values on the right. You need to find the HKEY_LOCAL_MACHINE \ SYSTEM \ CurrentControlSet \ Services \ Tcpip \ Parameters branch. For Windows 8, Tcpip can be replaced with Tcpip6.

In the value box, create a new one. This is done by right-clicking. The context menu selects "Create", then the new DWORD parameter, and is named Default TTL. What is it? This will be a static parameter for a constant lifetime value. Then right click again and select "Edit". The number should be decimal, and the value is 65. Thus, the system will transmit the packet's lifetime to 65, that is, one more than the "Android". That is, passing through the smartphone, it will lose one unit, and the provider will not notice the dirty trick. After the changes are made, you must restart the computer.

Now you can distribute the Internet to "Android", without using special software and tools.

Change to Linux

How is TTL changing on a computer running Linux operating systems? For Linux, changing the package lifetime changes one line in the terminal: sudo iptables -t mangle -A POSTROUTING -j TTL --ttl-set 65

Changing the lifetime of a packet on modems

You can change the TTL modem by changing the IMEI. This is an identification code unique for each device that has access to cellular networks. The whole problem is that there is no universal way. This is due to the fact that for each separately taken modem there should be a firmware, which will replace IMEI.

The site 4PDA has a selection of solutions for changing the lifetime on modems from different manufacturers and models. Also, there you can find detailed implementation of this task.

Changing the lifetime of the package on iOS

Using tweaks TetherMe can be changed to iOS TTL. What it is? This is a deb-application that unlocks modem mode on devices with iOS on board. The fact is that Apple allows some cellular network operators to block the function "Modem mode" at the level of SIM. This application allows you to activate it and use your phone as a modem.

Change TTL in MacOS

MacOS defaults to a lifetime of 64. If you want to change it, you need to enter the following command in the terminal: sudo sysctl -w net.inet.ip.ttl = 65.

However, with this approach, the value after the reboot will again change to 64. Therefore, it is necessary to perform a number of manipulations. At the root of the disk, there is a directory etc. It's hidden, but you have to get into it. The sysctl.conf file is created there. In it it is necessary to register only one line - net.inet.ip.ttl = 65. Well, of course, save.

To display this hidden folder in the Finder, go to the main disk and press the cmd + shift + G key combination. In the appeared window the name of the desired folder is entered, after which it will be found.

conclusions

There is such a thing as a USB TTL converter. However, it has nothing to do with the context of the article, and it should not be confused with the package lifetime. USB TTL converter is a kind of adapter for creating connections between USB devices and TTL logic.

The article explained in detail about TTL - what it is and what is needed. Several ways to change it will allow you to bypass the restriction on blocking traffic on some providers. This makes it possible to use the Internet everywhere.

Implementation on different devices is different, you can do it both with the help of software tools, and by changing system files manually. Some modems will have to be stitched, and under each version of the software.

These instructions can bypass the blocking of many providers that provide access to the Internet through a cellular network.