IP spoofing, also known as IP address forgery or a host file hijack, is a hijacking technique in which a cracker masquerades as a trusted host to conceal his identity, spoof a Web site, hijack browsers, or gain access to a network.

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Why is it difficult to catch “Anonymous” or “Lulzsec” (groups)?

I'm not security literate, and if I was, I probably wouldn't be asking this question. As a regular tech news follower, I'm really surprised by the outrage of Anonymous (hacker group), but as a ...
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3answers
5k views

How does IP address spoofing on the Internet work? Who can do it?

Someone recently told me that the NSA could impersonate pretty much anyone they want by using IP address spoofing on the Internet. But how would that work and to what extend is it true anyway? Could ...
21
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3answers
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Can I trust the source IP of an HTTP request?

As far as I've understood, if you try to issue a HTTP request with a spoofed IP address, then the TCP handshake fails, so it's not possible to complete the HTTP request, because the SYN/ACK from the ...
19
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6answers
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What security risks does IP spoofing bring?

By manipulating the TCP packet and changing the source address one is able to spoof the IP. As I understand it, you will not be able to set up a full handshake by doing this, as you will never receive ...
19
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4answers
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How are spoofed packets detected?

My assumption: When a firewall is configured to drop spoofed packets, it tries to ping (not necessarily ICMP) the source IP and sees if it belongs to a real host or if it's up, and if not, it drops ...
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2answers
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In what scenarios is relying on source IP address as a security control acceptable/unacceptable?

A number of questions on this site mention relying on source IP address as a control and in most of them it is dismissed as being unreliable. In what circumstances might using source IP address as a ...
17
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6answers
11k views

How does a server obtain the IP Address of a user?

How does a server obtain the IP Address of a user? Is it possible to fool the server by spoofing the IP Address?
17
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3answers
1k views

Vulnerable code suggested on OWASP?

Session Hijacking Prevention It is good practice to bind sessions to IP addresses, that would prevent most session hijacking scenarios (but not all), however some users might use anonymity tools (...
14
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3answers
6k views

How does the hacker manage to spoof a different IP address?

For the last 2 days, +/- every 15 minutes, someone is attempting to sign-in to my online email account. When I verify recent activity, the IP address (and the corresponding country) is different for ...
14
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2answers
4k views

Is IP spoofing relevant to TCP? Is it relevant for TLS or SSH?

I have read the TCP Connection Establishment on Wikipedia In brief the packets to start are SYN, with a (hopefully) random sequence number A from the client. SYN-ACK, responding, with A+1 and (...
13
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3answers
1k views

Are there valid reasons for spoofing an address?

This is a corollary to the question Why don't ISPs filter on source address to prevent spoofing?. Are there valid reasons to spoof an address?
13
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5answers
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Apache/Linux server, DoS attack from own IP

I have an unusual problem I've been trying to diagnose for a while: It's about a Debian server running a custom compile of apache 2.2 with PHP, Red5, MySQL 5.5 (standard binary), sendmail (distro ...
12
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4answers
9k views

Is it possible to pass TCP handshake with spoofed IP address?

Little time ago, me and my friends argued if TCP handshake can be passed with a spoofed IP address. Assume I have a https web server that allows only admin's IP numbers. Can anyone connect that web ...
12
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6answers
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What tools are available to identify which country a specific IP address is located in?

In trying to identify the country a user logs in from, or to block country ranges for whatever reason (for example regulatory requirements) what tools, whether online or offline, are available?
12
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4answers
2k views

Why don't ISPs filter on source address to prevent spoofing?

I'm under the impression that if all the ISPs were required to filter on the source IP address of all outbound packets, that spoofing would be reduced considerably. Are any ISPs implementing this ...
10
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2answers
8k views

How easy/difficult is it to spoof DNS? Are some scenarios safer/more risky than others?

Practically speaking, how easy difficult is it to spoof DNS? What scenarios are more risky than others? For example: A phishing email or twitter link that attracts users to click a hyperlink A ...
8
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5answers
20k views

Does chatting over Skype expose my IP address?

Is there a way to identify a person's IP address in Skype, when you're chatting with them? Does this depend on their Skype settings? And if you've recorded chat messages, can they lead to the actual ...
8
votes
4answers
825 views

IP Address spoofing?

According to: https://secure.wikimedia.org/wikipedia/en/wiki/IP_address_spoofing "this technique is mainly used when the attacker does not care about the response or the attacker has some way of ...
8
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4answers
1k views

How can a company reduce exposure to packet spoofing? What solution should exist, but doesn't?

I'd like to understand what anti-packet-spoofing technology exists (or should exist) to verify an inbound packet. Maybe this is as simple as a Cisco ACL, Firewall Rule, implemented at the network ...
8
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2answers
2k views

Spoofed IPv4 and IPv6 addresses over the internet

I have a few questions regarding IPv4 and IPv6 spoofing. Might as well just list them to be concise: What's the usual routing policy for ISPs' routers in regards to spoofed source addresses? i.e. if ...
8
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3answers
459 views

Verify a website user is behind corporate firewall?

We have a public ecommerce website hosted at our datacenter onsite. For people who are within the corporate firewall hitting the website I want to display profiling information about the request of ...
7
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2answers
1k views

Spoof IP adress after a TCP handshake

I know it is not possible to perform a successful TCP Handshake with a spoofed IP-Address. However I wonder: Is it possible to spoof the IP once a TCP handshake was performed successfully? For ...
7
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3answers
4k views

TCP Sequence Prediction and it's prominence in modern systems/networks

I have a question regarding your experience of TCP Sequence Prediction that I am hoping someone could help with. I am aware of how TCP Sequence Prediction works and how the connection can be hijacked ...
7
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5answers
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Preventing online voter fraud

As part of a promotional campaign, my company wants to launch a site where users (and potential users) of our product will be required to register and vote for certain choices. Depending on how ...
7
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1answer
252 views

Parabolic Denial Of Service — Would it work?

Would this DoS attack be effective: Attacker determines target (10.0.0.1) Attacker sends ack packets to a buch of web servers with a src addr of 10.0.0.1 Servers reply to 10.0.0.1 with syn packets ...
7
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5answers
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GET request with different IPs

I need to check vulnerability in my polling system. So I need to send GET requests but every time with different IPs. Can anyone suggest something?
7
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2answers
563 views

Is IP spoofing still a threat in the Internet?

I heard that IP spoofing is now mostly blocked by ISPs, especially on the consumer-grade links. Is there any research on the number of networks that still allow users to spoof an IP packet with an ...
7
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1answer
2k views

Brute force login attempt from spoofed IP's

I see that many of my WordPress installs are being hit with 1000+ failed login attempts using non-existing 'admin' account name. The requests come from different IP's every time, and I see IP's such ...
6
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6answers
9k views

Why can't we block DNS Amplification attack by blocking UDP packets or DNS response packet?

I mean if the attacker tries to ask all the open DNS resolver respond to a web server. The web server can just block its UDP ports. If the all the DNS response go to a Authoritative Nameserver(victim)...
6
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2answers
101 views

What information should I provide to a website or organization when notifying them that their domain may be sending out spam?

Over the past few days, I've received several spam emails coming from the addresses of a school district. I don't know much about email message headers, but since they contain numerous references like ...
6
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1answer
582 views

Ingress RFC1918 spoofing: How to handle it?

I've seen packets originating from RFC1918 addresses from two fairly large european ISP's (ASN1257 & smaller ASN35706) coming in on eBGP transit links lately, and I'm a bit puzzled why it wouldn't ...
5
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2answers
1k views

How does IP address spoofing of a bad address work?

While reading up on iptables, I saw this article from NixCraft recommending that a server block the following bad addresses: 0.0.0.0/8 10.0.0.0/8 127.0.0.0/8 172.16.0.0/12 192.168.0.0/16 224.0.0.0/3 ...
5
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3answers
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How secure can IP based login be?

From several security books and sites I understand that IP-based security (with which I mean: user is verified only by IP address) is a bad idea. Our idea is not new: we want a one-time validation and ...
5
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2answers
2k views

Why would the browser present the certificate for an unknown outside site?

The first time each day that I attempt click on the 'Mail' link from the Yahoo home page, my browser (Seamonkey) throws up a dialog with the title 'Secure connection failed'. The content in the ...
5
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1answer
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Spoofing email From address

Providing all legal measures are taken care of, what are some of the ways someone can spoof an email "From" field address and actually get the email to the recipient without spam filters getting in ...
5
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3answers
650 views

Solaris: IP Spoofing Across Ethernet Ports

Given a Solaris machine with two network interfaces corresponding to the separate ethernet ports in the back. 0: 192.168.0.5/255.255.255.0 1: 192.168.1.5/255.255.255.0 with /etc/defaultrouter set ...
5
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2answers
214 views

IP Spoofing: How secure is to control access by user’s public IP address?

We have a few Windows server VMs hosted in Amazon cloud. Users need to enter account and password to RDP to the VMs. The VMs’ RDP EndPoint (IP+Port) is public to the internet. As an extra security ...
5
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1answer
573 views

Can IPs be trusted inside a VPN?

Question I have several linux clients connected to an OpenVPN server. Each client is given a persistent IP based on their X509 Common Name. Can I trust these IPs ? Context I have Client1 and ...
4
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3answers
35k views

How can I trace the IP address of person in chat?

Is it possible to trace my IP address when I am chatting with others (with gtalk or Facebook)? If so, how could someone do that?
4
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2answers
2k views

IP forgery (theories are fine)

Is there any (practical/theoretical) way to forge your IP address? By forging i mean feed to the WEbsite the IP you want. let take PHP as example: You need me to think that your IP address is 225....
4
votes
3answers
1k views

Reveal the True IP of a User

Is there any best practice method (and preferably documented) way of revealing the True IP of a user using a HTTP(S) connection? I.e.: To be able to uncover the true IP from transparent as well as ...
4
votes
5answers
3k views

Is it trivial to bypass IP blocking?

There is a site with IP blocking. When a client makes too many invalid attempts when guessing e.g. password, then their IP address becomes blocked. I've heard about IP spoofing and similar attacks. ...
4
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1answer
1k views

172.16.33.197, 127.0.0.1 IP addresses in visitor logs

I have a website running Apache and PHP. I see that there are visitors with IP addresses 172.16.33.197 and 127.0.0.1. These addresses do not belong to our network. I get the visitor IP addresses with ...
4
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1answer
126 views

How to defend against a Spoofed-IP Blacklist DOS attack?

So I've implemented an IP Blacklist for the /login endpoint on my server. If any IP fails to login more than x number of attempts in x number of minutes the requesting IP is blacklisted for x number ...
4
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1answer
330 views

Explain the last part of how Mitnick hacked Tsutomu Shimomura with an IP sequence attack

I was reading up on why TCP ISNs need to be randomized, which led me to this write up by Tsutomu Shimomura. I understood how IP address spoofing and predicting the ISN helped the attacker establish a ...
4
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1answer
116 views

Spoofing LAN IP Address Traffic

To give as much detail as possible, I am doing a Pentest for a client that has quite a few "terminal systems" meaning that they are simply a box with a connection back to the main server. These ...
3
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3answers
2k views

How can I make it more difficult for a user to create multiple accounts?

I would like to know the best way to increase security on a website so that the a single user can't create multiple accounts. What all of a user can be traced? I'm thinking: IP address Mac address ...
3
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4answers
4k views

How can an internet contest verify unique votes with only an email as an input parameter?

For my computer security course we are brainstorming different ways to use attributes for a unique user (that are readily available over a network) to prevent various mischievous activities. We've ...
3
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2answers
2k views

Does “loose source and record route” drop the source address?

Is the source IPv4 address lost when a person uses "loose source and record route" and the destination address is put before the end of the list of addresses through which routing should occur? It ...
3
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5answers
9k views

Stopping users from spoofing an IP

I have a MikroTik router (that has firewall and scripting capabilities) that is acting as a DHCP server for the 192.168.1.0/24 subnet. Is there any way I can stop it from passing traffic from a user ...