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I don't fully understand how packet sniffing works, but the gist I get from it is that if someone is logged on the same network as you, they can sniff packets for unhashed passwords and... well, that's really enough damage.
The solution, I've read, is to only go on networks that are secure when doing bank stuff, but my issue is that the only secure network I have is a school wide one (dorms). Imaginably, the school wouldn't set up a network so open to password theft, but the only thing I can think of stopping the bad guys is that we log in with our student ID. All they would need is someone else's ID and password and (if my understanding is correct) they could packet sniff pretty much everyone in the hall using the same router without being traced.
Are my fears justified, and if not why? And if so, also why?
Thank you
Speaking generally, you can't sniff transmissions between a client and a bank server since the communication uses public key encryption. That said, SSL is still vulnerable to man-in-the-middle attacks - beware of notices/alerts about unrecognized certificates.
Regarding privacy on non-HTTPS websites, it depends on how your network is set up. If it's a standard WPA2 setup then all of your unencrypted traffic is visible (easily) to anyone who is in transmission range of your computer and has the WiFi password. You can install HTTPS Everywhere from EFF (https://www.eff.org/https-everywhere‎) which helps secure your communications on many common websites - Facebook, Twitter, etc.
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If I gave my SSL certificate & private key being used on website mydomain[dot]com to some hacker, would the hacker be able to hijack / intercept the connection or misuse in any way?
Right, so basically, "What's the point of protecting an SSL certificate's private key?"
The proper name for the attack you're describing is "Man in the Middle (MitM) attack".
As the name implies, the attacker needs to be in the middle [source article for the image]:
At this point, you will open an HTTPS connection to the attacker and because they have the certificate and private key, you can't tell that you are not talking directly to the legitimate web site. The attacker then opens another HTTPS connection between themselves and the server; because they are re-transmitting your messages (including your login) the server can't tell that they are not talking directly to you. The attacker is "in the middle".
How does the attacker get in the middle? Maybe they are on the same hosting service as you and have somehow tricked the service provider to route your traffic to them. Maybe they are one of the legitimate routers on the internet. Maybe they have used techniques such as BGP Hacking to convince the legitimate routers that they have a fast route to your server. Maybe they are in the same wifi is the victim and have used ARP Spoofing to convince the victim that their laptop is the wifi router and all traffic should go through it. Lots of ways, all of which require "an extra step" in order to perform the attack.
Summary: An attacker with your SSL certificate and private key can't do anything directly, but it opens up a whole category of attacks if they also have the ability to manipulate network traffic to put themselves "in between" your site and the victim.
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After finding someones ip you can easily send pings to them to make DOS attacks. Me and my friend tried to make a defense against them and wanted to know how a low level attacker can send this DOS attacks. When one of us sent pings to the other using cmd when we were connected to the same modem(wifi) it succeed in sending pings. But when we were on different networks it failed and sent a message like "Request timed out". I assume this is a failure message but I've some questions in this matter.
I won't write the command to make DOS attacks since I don't want to encourage anyone in making those and anyone who is knowledgeable in this subject already knows how to do that.
//Assume that attacker knows the ip of the victim.
Questions
Can a computer be successful enough to slow down the second computer if he sends infinite pings? If so in how much time(approximately.)(assume their computers are same.) What can be the worst result for the victim?
How can someone be successful in making DOS attacks to people who are connected into different networks from cmd? And how can I take measures against them?
This will not work over the internet if the victim's router is set not to send ICMP replies to ping requests.
Can a computer be successful enough to slow down the second computer
if he sends infinite pings? If so in how much
time(approximately.)(assume their computers are same.) What can be the
worst result for the victim?
Not significantly. What you need is an amplification attack - that is the victim's computer has to do more work than you for each request. Sending a reply to a ping is minimal work and involves sending the same amount of bytes back, so you are not slowing the victim machine anymore than your own.
How can someone be successful in making DOS attacks to people who are
connected into different networks from cmd? And how can I take
measures against them?
You would be better off using a software tool to do this, or by setting up a botnet to do a distributed denial of service instead (DDoS). Usage of such tools are probably illegal depending on your jurisdiction and you should get full permission if testing this from the owners of all networks and systems where your traffic would flow.
Mitigating DDoS is the million dollar question. Services such as CloudFlare can help. It all depends on what you need to protect and who from.
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I have a client app that faces the internet, but only clients will access. The site should never be indexed or crawled or viewed outside of our clients. We always concerned about DDOS and attempts to gain access. If the system can add one more level of being hidden, or harder to find, I don't see the negatives.
Users will never have to enter the domain name (think kiosks), and admins can use bookmarks. Yes, security by obscurity is no solution and never relied upon. But if you can add it to an existing and robust secured system, why not?
Is there any downside to having a random domain name like j398sh3-3nj23j.com?
I would love to hear some thoughts and opinions.
If you're never using where anyone will see it (even by rDNS on an incoming connection from your server), then the only real drawback is that you're paying for it when you could as easily use a random subdomain under a domain you already control (e.g. j398sh3-3nj23j.example.com).
But it'll provide zero protection from DDOS or attempts to gain access, as anyone who is in a position to extract a normal domain name from your client app will probably be able to extract this random domain name just as easily, and they may not even bother with domain names and just get the IP address your client is connecting to anyway.
Emphatically speaking, that's useless. As was pointed out above, using some subdomain of your own would cost less, be saner, and have more utility.
If you have a number of nodes on a private network that is not physically private, use a good VPN system and machine authentication with certificates. If you do that, nothing is accessible except the Internet-facing VPN software, and that can easily ignore anything that's not legitimate.
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I'll be using a shared Internet connexion starting this September at my school and I was wondering about what someone sniffing traffic with Wireshark may find there. I am not planing to do this myself but I feel I ought to know more about it if I want to sometimes work on my website during class.
Basically, isn't every non-SSL website that asks you for a password and an e-mail totally unsecure to log on on a shared connexion? When you know how many people use the same password for all their web/laptop/mobile accounts, it doesn't take long to get access to someone's all private data if you manage to sniff one password and e-mail.
As for me, I am already looking at how to secure my FTP connexions, but what about my users who log through HTTP? Unless I buy a SSL certificate (which I don't want, the site's too small), they are going to get more exposed to Wireshark sniffers all over the world, right? Isn't this where login tools such as OpenID become handy for small communities, since they do provide a free encryption of passwords?
OpenID and SSL are completely unrelated. OpenID's purpose is to consolidate and give ownership of a user's identity to the user, while SSL is used to keep a user's traffic with your site secret (encrypted). You can use OpenId to keep track of the user (like Stackoverflow does) and still not use SSL for the content pages.
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I have been a .net developer for the past three yrs. Just curious to know about the network security field. What kind of work does the developers working in these area do? I really have not much idea about network security but what my understanding is these people are involved in securing network, preventing attacks on network as obvious. Could any one please give me some details about this field and also what does it take to move to this field.
Take a look at "Security Engineering" by Ross Anderson. The first edition and part of the second are available for free online here. While he talks about many non-network issues, the principles mostly apply.
Network security is a vast subject. On the developer side, I think you would most likely be concerning yourself with lots of encryption schemes and process security. There are basic things like using SSL for network traffic of a program to more advanced subjects like preventing any traces of a sensitive operation from remaining in RAM after a program has processed (and probably encrypted) it.
Today, you would need to become an expert in TCP/IP protocols. Everything from ARP, DNS, UDP, ICMG, BGP, and on and on. Most networks are IP-based, with IP-based firewalls. The firewalls will allow, for example, "TCP traffic on port 80" to come through. You need to be able to understand if that traffic is valid web surfing, DOS attack, or otherwise malicious. This can only be accomplished with detailed understanding of how IP networks work. Ditto for other protocols like DNS. In addition, lower-level understanding of ethernet communications and other means of transport (like cell phone networks or WiFi networks) would be important. I suppose it depending on what you mean by "network security" - to me this is below the application layer.