Hackers are always looking for new ways to hide IP addresses. This isn't only about remaining anonymous; IP addresses can also be blocked if they appear to be the source of malicious activity.

One option for keeping IP addresses hidden is to use IP spoofing. It can be used to mask thousands of IP addresses and make a victim think that an attack is coming from anywhere.

So what exactly is IP spoofing and how can you protect against it?

What Is IP Spoofing?

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IP spoofing is an attack where the attacker hides the source of IP packets. This causes the target of an attack to believe that they are receiving traffic from a different source.

This is useful not just for hiding the identity of the attacker; many security techniques are based on IP addresses and IP spoofing is a useful tool for rendering those techniques ineffective.

How Does IP Spoofing Work?

All internet traffic is sent in packets. Each packet has an IP header which includes the source IP address and the destination IP address.

During an IP spoofing attack, the attacker changes the source IP address before the packet is sent. When that packet is received, the IP address will appear legitimate but actually has nothing to do with the attacker.

The fraudulent source IP address can be random. Random IP addresses can be generated automatically, or the fraudulent IP can be copied from elsewhere.

A copied IP address is useful because it allows the attacker to pretend to be a specific person. For example, IP spoofing can be used to make the victim think that they are talking to a device that they already trust.

What Is IP Spoofing Used For?

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IP spoofing can be used to access some restricted servers, and perform both DDoS and Man-in-the-Middle attacks.

Avoiding IP Authentication

IP addresses are often used for authentication purposes; for example, to determine whether or not a particular user is allowed to access a particular server or network.

If an attacker has the name of a trusted IP address, IP spoofing can imitate that user. This would allow the attacker to access any server that is only protected using IP authentication.

This technique can be used to plant malware, steal data, and/or launch a ransomware attack.

DDoS Attacks

DDoS attacks are based on the idea that a server can only handle a certain amount of traffic. They attempt to overwhelm servers by sending traffic greater than that amount.

DDoS prevention techniques are based on differentiating between legitimate and malicious traffic. IP spoofing can prevent this from occurring.

A successful DDoS attack can render a server unusable, and so take both websites and entire networks offline.

Man-in-the-Middle Attacks

During a Man-in-the-Middle (MITM) attack, an attacker intercepts communication between two parties. Each believes that they are talking directly to the other but all communication is actually being routed through the attacker.

In order for a MITM attack to be effective, the attacker obviously needs to remain hidden. IP spoofing allows them to achieve this by copying the IP address of the other party.

A successful MITM attack allows the attacker to steal information and/or modify information before it reaches its recipient.

Is IP Spoofing Only Used by Hackers?

IP spoofing is primarily used by hackers. But it can also be used for legitimate purposes. For example, a website owner might use this technique to test how their website performs under pressure.

IP spoofing can be used to simulate real visitors. This allows developers to understand how a website will react to large amounts of traffic.

How to Protect Against IP Spoofing

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IP spoofing is effective because it's not always possible to detect that it is occuring. Here are a few ways to make IP spoofing more difficult.

Monitor Networks for Unusual Activity

IP spoofing is always performed for a reason. If you cannot tell that a specific IP address has been spoofed, you may still be able to detect an IP spoofing attack by monitoring your network carefully for other signs of malicious behavior.

Use Alternative Verification

IP spoofing allows attackers to bypass IP authentication. Any type of remote access should therefore be required to use alternative authentication and verification methods. One example of this is to require all machines on a network to use authentication based on key exchange.

Use IPv6 on Websites

IPv6 is the latest Internet Protocol. One of its advantages over IPv4 is that it adds extra encryption and authentication steps. This makes IPv6 websites more difficult to target with IP spoofing.

Use a Firewall

A firewall can be configured so that it detects some types of IP spoofing, achieved using ingress and egress filtering.

Ingress filtering inspects packets and rejects anything that doesn't have a trusted IP address.

Egress filtering inspects outgoing packets and rejects anything that doesn't have a source IP from within the network. This prevents outgoing IP spoofing attacks.

Other Types of Spoofing Used by Hackers

Spoofing can roughly be defined as the act of impersonating something else. This is a useful concept for hackers because it allows them to gain the trust of victims. Other examples of spoofing include:

  • Email Spoofing: An attacker will modify the message header of an email so that it appears to come from somebody else.
  • ARP Spoofing: This technique associates an attackers MAC address with a legitimate IP address by using spoofed ARP messages.
  • DNS Spoofing: This allows an attacker to redirect traffic from a requested website to a website that the attacker owns.

Protect All Networks Against IP Spoofing

IP spoofing is an example of the lengths that hackers will go to to hide their activities. It also demonstrate that any security measure based solely on IP detection can potentially be beaten.

IP spoofing cannot always be prevented, but you can greatly reduce its effectiveness. And this is an important step to take for any network administrator who wants to keep hackers out.