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An example of the fragmentation of a protocol data unit in a given layer into smaller fragments. IP fragmentation is an Internet Protocol (IP) process that breaks packets into smaller pieces (fragments), so that the resulting pieces can pass through a link with a smaller maximum transmission unit (MTU) than the original packet size.
IP fragmentation attacks are a kind of computer security attack based on how the Internet Protocol (IP) requires data to be transmitted and processed. Specifically, it invokes IP fragmentation, a process used to partition messages (the service data unit (SDU); typically a packet) from one layer of a network into multiple smaller payloads that can fit within the lower layer's protocol data unit ...
When fragmentation is performed, each IP fragment needs to carry information about which part of the original IP packet it contains. This information is kept in the Fragment Offset field, in the IP header. The field is 13 bits long, and contains the offset of the data in the current IP fragment, in the original IP packet.
This fragmentation process takes place at the internet layer. The fragmented packets are marked so that the IP layer of the destination host knows it should reassemble the packets into the original datagram. All fragments of a packet must arrive for the packet to be considered received. If the network drops any fragment, the entire packet is lost.
Loose Source Routing is an IP option which can be used for address translation. LSR is also used to implement mobility in IP networks. [3] Loose source routing uses a source routing option in IP to record the set of routers a packet must visit. The destination of the packet is replaced with the next router the packet must visit.
To avoid fragmentation in the IP layer, a host must specify the maximum segment size as equal to the largest IP datagram that the host can handle minus the IP and TCP header sizes. Though there is no minimum required MSS defined in IETF RFCs , there is a minimum MTU, and so a default MSS is calculated by subtracting the minimum IP and TCP ...
An IP packet has no trailer. However, an IP packet is often carried as the payload inside an Ethernet frame, which has its own header and trailer. Per the end-to-end principle , IP networks do not provide guarantees of delivery, non-duplication, or in-order delivery of packets.
Unix-like operating systems commonly implement IP address blocking using a TCP wrapper, configured by host access control files /etc/hosts.deny and /etc/hosts.allow.. Both companies and schools offering remote user access use Linux programs such as DenyHosts or Fail2ban for protection from unauthorized access while allowing permitted remote access.