Stack Exchange Network

Stack Exchange network consists of 175 Q&A communities including Stack Overflow, the largest, most trusted online community for developers to learn, share their knowledge, and build their careers.

Visit Stack Exchange

Questions tagged [network]

Security of network infrastructure and network traffic. For questions about security of network equipment, topology, protocols, traffic, administration, and configuration. Related tags: [packet], [firewall], [network-scanners], [network-access-control].

118
votes
13answers
296k views

Can my employer see what I do on the internet when I am connected to the company network?

This is an attempt at a canonical question following this discussion on Meta. The aim is to produce basic answers that can be understood by the general audience. Let's say I browse the web and use ...
61
votes
6answers
397k views

If someone hacks my wi-fi password, what can they see and how?

If someone knows my wifi password (be it WEP or WPA) what can they see? Do they just see URLs I visit, or can they see everything in my browser, or even everything I do on my computer? Does using ...
74
votes
5answers
34k views

What techniques do advanced firewalls use to protect againt DoS/DDoS?

It is hard to protect a server against Denial of Service attacks, DoS/DDoS. The two simple ways I can think of is to use a server with much resources (e.g. CPU and memory), and to build the server ...
56
votes
3answers
6k views

Is it common practice for companies to MITM HTTPS traffic?

My company has just introduced a new VPN policy whereby once connected all traffic is routed the company network. This is to allow for improved monitoring of data theft. It would appear that this ...
85
votes
5answers
91k views

Should SSL be terminated at a load balancer?

When hosting a cluster of web application servers it’s common to have a reverse proxy (HAProxy, Nginx, F5, etc.) in between the cluster and the public internet to load balance traffic among app ...
37
votes
5answers
8k views

Security impact of using a public password for free WiFi

We have a WiFi network that we want to be public and free. Does having a password that is known to everyone provide any additional security advantage to the people using this network as opposed to ...
98
votes
4answers
150k views

Is it a bad idea for a firewall to block ICMP?

This question was inspired by this answer which states in part: The generic firewall manifest file finishes off by dropping everything I didn't otherwise allow (besides ICMP. Don't turn off ICMP). ...
81
votes
10answers
103k views

Why do people tell me not to use VLANs for security?

I have a network, where a have a couple of VLANS. There is a firewall between the 2 VLANs. I am using HP Procurve switches and have made sure that switch-to-switch links accept tagged frames only and ...
39
votes
6answers
66k views

Can I detect a MITM attack?

Based on this question here: Are "man in the middle" attacks extremely rare? Is it possible to detect man-in-the-middle attacks, and if so, how would one go about it? In addition, what if ...
29
votes
7answers
3k views

How to secure a WiFi network?

What do I have to do to secure a WiFi network? Is there any best practices? I have been recommended to use WPA2 encryption on the router, is that enough? What can I do to improve the security even ...
13
votes
2answers
15k views

How can someone hack my PC if I am connecting to the internet through NAT?

If I own a private IP address, 192.168.2.1 for the sake of it, and I am physically connected to my router, which it's internal interface is 192.168.2.254 and it's external interface is some public IP ...
9
votes
2answers
1k views

WPA3 announced. Really needed?

It seems Wi-Fi Alliance announced WPA3 for the end of 2018. Anybody knows exactly what is new? features, security improvements, etc... Is it because of Krack attack? I thought patching WPA2 is enough....
5
votes
2answers
2k views

Encrypt and Authenticate localhost-traffic?

I have some app-components on the same machine but in different languages which need to communicate. I am using socket communication over localhost to do so. The data transferred is confidential. ...
136
votes
8answers
20k views

Are “man in the middle” attacks extremely rare?

In "Some thoughts on the iPhone contact list controversy and app security", cdixon blog Chris Dixon makes a statement about web security Many commentators have suggested that a primary security ...
30
votes
5answers
42k views

How to find out that a NIC is in promiscuous mode on a LAN?

How to find out that a NIC is in promiscuous mode on a LAN?
45
votes
6answers
58k views

Security risk of PING?

I have been told that PING presents a security risk, and it's a good idea to disable/block it on production web servers. Some research tells me that there are indeed security risks. Is it common ...
19
votes
1answer
12k views

How can I detect real location of the user through their IP address?

There were many ways to detect the user's IP, for instance we could get it through a single click link or through any other medium of communication where we could get the user's IP. But the tedious ...
15
votes
1answer
2k views

Kaspersky Antivirus “secure connection scan” as broken as Superfish?

I've read a lot about Superfish (and similar ad-ware) lately and I basically understand the vulnerability to MITM attacks. But I'm actually wondering if the "secure connection scan" by Kaspersky ...
19
votes
1answer
6k views

SFTP, FTPS and SecureFTP differences and security implications

What are the basic differences and security implications of using SFTP, FTPS and SecureFTP.
5
votes
3answers
2k 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 ...
12
votes
2answers
29k views

Are open ports dangerous?

I have forwarded port 80 to WAMPServer and 25565 to the MineCraft-server running Bukkit. Am I vulnerable to attacks. Can hackers attack me if WAMP-server is running or if it is not running, or will ...
200
votes
8answers
181k views

What is the difference between SSL vs SSH? Which is more secure?

What is the difference between SSH and SSL? Which one is more secure, if you can compare them together? Which has more potential vulnerabilities?
62
votes
8answers
115k views

What is the difference in security between a VPN- and a SSL-connection?

I would like to design a client-server application where the server is placed on Internet. I assume that I could set up the client-server connection using VPN (is it using IPSec?) or using a SSL ...
39
votes
7answers
14k views

Port Knocking is it a good idea?

Normally for a server I like to lock down SSH and other non-public service to only be accessible by certain IP addresses. However this is not always practical if the business doesn’t have static IP ...
30
votes
3answers
11k views

How do DoS/DDoS work?

In the last days one could frequently read about attacks from anonymous and LulzSec against different platforms like Sony or HBGary etc. Yesterday for example they DDoS'ed soca.gov.uk and jhw.gov.cn. ...
23
votes
6answers
6k views

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 ...
32
votes
7answers
107k views

Why is WPA Enterprise more secure than WPA2?

In personal mode WPA2 is more secure than WPA. However, I have read that WPA Enterprise provides stronger security than WPA2 and I am unsure exactly how this is achieved.
14
votes
3answers
15k views

What is the difference between SSH and IPsec?

There seems to be similar encryption going into both. They both use asymmetric (RSA, elliptic curves, etc) for the initial key exchange, then go to some symmetric (AES, Blowfish, etc) protocol. I'm ...
13
votes
4answers
19k views

How can I keep a roommate from seeing my web activity?

I have a roommate who is a network security engineer and I think he hacked our home network and now knows what sites I am visiting and what I am doing online. Although he is not stealing anything I ...
95
votes
8answers
17k views

How can I protect my internet-connected devices from discovery by Shodan?

There's been a lot of buzz around this recent CNN article about Shodan, a search engine that can find and allow access to unsecured internet-connected devices. Shodan runs 24/7 and collects ...
57
votes
10answers
112k views

Why block outgoing network traffic with a firewall?

In terms of a home network, is there any reason to set up a router firewall so that all outgoing ports are blocked, and then open specific ports for things such as HTTP, HTTPS, etc. Given that every ...
48
votes
13answers
42k views

DDoS - Impossible to stop?

Is it possible - in theory - to stop1 a DDoS attack of any size? Many people claim it's impossible to stop DDoS attacks and tell me I just shouldn't mess with the wrong people on the internet. But ...
24
votes
3answers
3k views

How does Convergence (CA replacement) prevent its notaries from being MITM'd as well?

I have been looking into Convergence and how it works, but I cant figure out how it is effective against a MITM attack that happens near the target system. My understanding is that Convergence works ...
17
votes
4answers
11k views

Best way to report a foreigner attacker's ip to authorities?

I have been under attack last week and I was able to trace down the attacker and get his IP address. The attacker was located in Germany but I live out of Europe? From your experience what is the ...
29
votes
7answers
45k views

Is it still unsafe to email credit card number nowadays?

We all know not to do it, but someone emailed my credit card number and cvv code to my gmail. I'm wondering if the risk is so low I don't have to call to cancel my card. The email is sent from a ...
22
votes
2answers
3k views

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 ...
10
votes
2answers
3k views

How does HSTS stop MitM attacks?

I know that until a few years ago, someone could set up a fake wireless AP, and use something like SSLStrip to lure the victims into connecting to insecure versions of the major websites, such as ...
7
votes
4answers
3k views

Email header IP address

Do the IP addresses in an email header include information from the device from which the mail is being sent, or from the mail server?
17
votes
5answers
4k 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 ...
17
votes
3answers
9k views

Can an attacker sniff Mac addresses on a wifi?

If an attacker turns on wifi but doesn't have the security key to connect to an access point in range, can he still sniff packets that travel between the access point and clients connected to the ...
9
votes
2answers
1k views

Any advantage to securing WiFi with a PSK, other than to keep out unauthorized

As I understand WiFi with a PSK, such as WPA(2)-PSK or WEP, anyone on the same network can decrypt anyone elses packets because everybody has the same key. In which case, if you are not going to ...
6
votes
7answers
7k views

Scanning A Subnet Externaly

Scenario: I have a router with a public IP address provided by the ISP and two hosts behind the router with a private IP (192.168.x.x). Is it possible to perform a port or vulnerability scan of a ...
119
votes
12answers
23k views

Is there a legitimate reason I should be required to use my company's computer? (BYOD prohibited)

I just got a new job at a medium-sized (~100 employees) company and one of the first things I was told is that I cannot use my own computer, because I need to be able to connect to their network, ...
95
votes
12answers
31k views

Landlord will be watching my data traffic, as mentioned in the lease agreement

I am moving to Germany, and in the contract I signed I had to accept that all my data traffic can/will be checked by the apartment owner. The contract states: Flatrate, aber hinter 30GB Tarif ...
54
votes
3answers
249k views

What is the real function and use of a DMZ on a network?

I read the article on Wikipedia describing what a DMZ (demilitarized zone) is on a network, but am still failing to grasp both how it is set up (ie: is it within the main network or sequestered away?) ...
42
votes
5answers
52k views

With IPv6 do we need to use NAT any more?

I'm wondering how to use NAT with IPv6. Seems that you don't even need it any more. So what exactly is the concept behind firewall configurations in IPv6 environments?
66
votes
8answers
50k views

Are powerline ethernet adapters inherently secure?

I have 2 Zyxel PLA407 powerline adapters. Router is downstairs connected to one adapter, other adapter is upstairs about 30 feet away connected to a desktop. I have a house, not an apartment or ...
23
votes
2answers
10k views

Reject IP packets with an ICMP error, or just drop them?

Consider an internet-facing host (the outer firewall). What should be done with undesired traffic: just drop it, or send back an ICMP error such as port unreachable? (In Linux terms: iptables -P DROP ...
23
votes
5answers
7k views

Access to a router's GUI

During a recent visit to a coffee shop, I noticed that they hadn't bothered changing their default user name and password for their router. I realise that someone could log on and be annoying to ...
18
votes
4answers
60k views

How to tell if you're being ARP poisoned?

I am having some issues at work and there is a new network admin in place. I think I am being monitored so decided to run ArpSpy X in two scenarios: Over WiFi bridge plugged into Cisco router to took ...