Is it better to have a higher or lower value for ttl?

Of course it's small!

TTL is a value in IP protocol packets that tells a network router if a packet has been in the network for too long and should be dropped. There are many reasons why a package cannot be delivered to its destination within a certain period of time. For example, an incorrect routing table can lead to an infinite loop of packets.

One solution is to discard the packet after a certain period of time and give the sender a packet that the sender decides whether to resend or not. The initial value of TTL is usually the default value of the system, which is an 8-bit domain in the header. The original idea of TTL was to determine a time frame beyond which packets would be dropped.

Since each router has to reduce the TTL domain by at least one, TTL usually represents the maximum number of routers that a packet can pass through before being dropped. When the count reaches 0, the router decides to drop the packet and sends an ICMP packet to the original sender.

The default TTL in Windows 95 98 is 32. It has been suggested that when reaching a node is difficult, this value should be set to use the TTL value for both the tracerouter in an attempt to reach a given host or trace a route to that host. TraceRoute sets the TTL value of the packet to a small size so that it is continuously dropped by each router on the way to its destination.

The time between sending a packet and receiving an ICMP packet is used to calculate the time from one router to another.

With the multiplexed IP protocol, the TTL value represents a range of packet coatings. There are the following transformations: 0, limit on the same host 1, limit on the same subnet 32, limit on the same node 64, limit on the same region (128), limit on the same continent (continent) 255, because the default TTL value of different operating systems is different, so there is an article that says that the type of the target system can be judged by the returned TTL value, which is correct, but it is not a function of TTL, just an application of TTL understanding.

The value of TTL can be modified. Some special systems (e.g., NIDS) define special TTL values to deny unauthorized access to data. We can use the -i parameter to specify the TTL value when executing the ping command, you can set the TTL to 0, and the packet will be discarded immediately.

Sometimes we run a ping command, but when we slow the packet, we send another address with an English prompt (roughly meaning that the TTL is invalid), which means that the TTL carried by the packet is 0 or less than the TTL value allowed to pass through the next network segment before it reaches the destination (that is, when it reaches the return IP location), and the packet has been dropped by the route.

For us, the value of TTL can easily calculate how many routers your device (such as the system) has passed through when ping it, and its size has no special advantage, you can change the value of TTL by modifying the registry. If you want to make it bigger, change it to a bigger one, and the general administrator changes its size to prevent hackers from ping it and getting the default TTL value of the system to determine what system it is and how many routers it has passed. (If you want to change it to a smaller one, you can change it too small, because the TTL value of your outgoing data will be reduced by one every time it passes through a router, and when it is reduced to zero, the router will not be transmitting data, but will directly discard the data with a TTL value of 0.)

"TTL" stands for Time to Live

First of all, let's understand the meaning of "TTL", which is an abbreviation for Time to Live, and this field specifies the maximum number of network segments that IP packets are allowed to pass through before they are dropped by the router. It may be abstract to say so. Let's take a look at the data of the ping command, as shown in the figure:

Ping the server.

In the picture above, I pinged the server (4 times by default under windows).

The byte represents the size of the packet, the time as the name suggests is the return time, and the "ttl" means the time to live of the packet, of course, what you get is the remaining time to live. TTL is used to calculate the consumption time of packets in the router, because the consumption time of most routers is less than 1s, and the time less than 1s is calculated as 1s, so the TTL of the packet does not pass through a router node is reduced by one.

So what is the value of TTL in the first place? TTL is different by default for different operating systems. By default, the TTL value is 64 or 255 for Linux systems, 128 for Windows NT 2000 XP systems, 32 for Windows 98 systems, and 255 for Unix hosts.

In the figure above, we can see that the TTL value of the packet returned by the ping server is 56 (usually looking for the value of 2 N and the closest value to the return value), so it passes through 64-56=9 routers on the way.

For another example, I ping my own IP, and the result is as follows:

Ping the local calculator.

You can see that when I get the TTL is 128, then I pass through 128-128=0 routers on the way, that is, I don't need to go through any router to send packets to myself, so the TTL value is 128, which means that my packet lifetime is 128.

Smaller ping ttl is better? Wrong!

Based on the analysis of the above examples, it is obviously wrong to say that the smaller the value of "ttl", the better, on the contrary, it should be said that the larger the value of "ttl", the better, because the larger the value of "ttl", the less the packets are sent through the router, and the less they pass through the router, the faster they reach their destination, and of course, the faster they will reach their destination.

TTL isIP protocolA value in the packet that specifies which datagrams are allowed to pass through before being dropped by the routerCIDR blockQuantity.

Difference 1: The number of network segments allowed to pass through before the specified datagram is dropped by the router is different, one is 128 and the other is 126.

Difference 2: Different ways; ttl=128 indicates that you can communicate directly with the other party. ttl=64 communicates across multiple routers.

Difference 3: The effective time is different; 64 takes effect faster than 128.

TTL is an abbreviation for Time to Live, and this field specifies the maximum number of network segments that IP packets are allowed to pass through before they are dropped by the router. TTL is an 8-bit field in the IPv4 header. In the IPv4 header, TTL is an 8-bit field that is located on the 9th byte of the IPv4 packet.

The role of TTL is to limit the time that IP packets can exist in a computer network. The maximum value of TTL is 255, and a recommended value for orange coarse TTL is 64.

Although TTL literally translates as the time it can survive, in fact TTL is the maximum number of hops that an IP packet can have in a computer network. The TTL field is set by the sender of the IP packet, and on the entire ** path of the IP packet from the source to the destination, every time it passes through a router, the router will modify the TTL field value, and the specific method is to subtract the TTL value by 1, and then the IP packet ** out.

TTL stands for Time to Live so that packets cannot be passed endlessly in the network, each time it passes through a router, TTL is reduced by one, and when TTL is 0, the packet is dropped by the router.

Feel free to ask.