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What Is IP Spoofing (IP fraud): It is a specific technique used by hackers to gain unauthorised access to computers. The concept of IP spoofing first appeared in academic publications in 1980. The IP Spoofing technique, which can be translated into English as IP identity fraud, is generally used to conceal the source of a DDoS attack.
At its core, IP spoofing or IP fraud involves cyber attackers concealing their identity with the aim of carrying out cyber attacks against victims. In DDoS attacks, concealing the source also makes it harder to block or detect the cyber attack.
TCP packet headers contain information such as port number and connection details. Ethernet headers also include specific information such as MAC addresses for source and destination. For example, if a packet is encrypted for security (e.g. TLS), it must have a TLS header.
By modifying the IP header to include a different address, an attacker can make a packet appear to have been sent by a different machine. The computer carrying out the attack cannot see the real source, and the response is directed to the IP address written in the (modified) header information. IP spoofing can theoretically be carried out on all protocols. In practice, however, it can be carried out on applications that use UDP, but not on those that use TCP. This is because TCP requires a three-way handshake and the sequence number in the packet header is unpredictable.
IP spoofing is frequently used in DDoS attacks. The aim of such attacks is to overload the target computer to a degree that prevents it from responding and fills its capacity. Since each spoofed packet appears to come from a different address, filtering becomes more difficult.
Through IP identity fraud, an intruder sends messages to a computer system that contain an IP address indicating the message originates from a different IP address than it actually does. If the aim is to gain unauthorised access, the spoofed address is made to appear to the target as a connection from a host it trusts.
To successfully carry out an IP identity fraud attack, cyber attackers first need to identify the IP address of a machine that the target system considers a trusted source. Hackers can use various techniques to find the IP address of a trusted host. Once they have this trusted IP address, they can modify the packet headers they send, making the packets appear to come from that host.
Unlike many other types of attacks, IP spoofing was known by security experts to be theoretically possible before it was used in real attacks. Although the concept behind this technique had been known for some time, Robert Morris proved it could also be realised in practice by identifying a security weakness in the TCP protocol.
IP Spoofing attacks are not used as frequently as they once were. The most important reason for this is that organisations have become more security-conscious. In particular, many ISPs block IP spoofing. However, identity fraud continues to be used as an effective attack type in today’s world.
The most significant danger arising from IP deception is that some firewalls do not inspect packets that appear to have come from an internal IP address. If they are not configured to filter incoming packets whose source address is in the local domain, they will be very easy to bypass.
Configuration Examples:
You will need to configure Ubuntu Server to prevent IP spoofing. Log in to Ubuntu Server and, after logging in, run the command “sudo nano /etc/host.conf”. The host configuration file will open. The host.conf configuration file contains configuration information specific to the resolver library. Change the line that reads multi on to nospoof on. At this point, by adding the nospoof value to the DNS resolver library, an attempt is made to prevent host name spoofing.
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