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What stops an internet router from sniffing my traffic?

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Packets travel through internetworks, and take many routes through internet routers. On each route that forwards traffic to another until reaching the ultimate destination, what stops them from viewing the packets they receive/forward?
asked Dec 11, 2013 by Naughty.Coder  
did you know that if you capture all the packets in an SMTP transmission, dump their data and convert it back to text (unicode nowadays, used to be ascii), you can read the email with little or no modification? people refer to email as a postcard, because there is no envelope to hide it from view as it passes between your host and the server.

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Short answer : you can't prevent them from sniffing your traffic, but you can make it meaningless for them by using encryption.

Either use encrypted protocols (HTTPS, SSH, SMTP/TLS, POP/TLS, etc.) or use encrypted tunnels to encapsulate your unencrypted protocols.

For example, if you use HTTPS instead of HTTP, the content of the webpages you fetch will not be readable from those routers.

But remember that they can still save the encrypted packets and try to decrypt them. Decryption is never about "can or can't", it's about "How much time does it take". So use ciphers and key lengths suitable for the degree of privacy you need, and the "expiration time" of the data you want to "hide". (meaning if you don't care if someone gets it a week after the transmission, use a strong protocol. If it's an hour, you can lower the key length)
answered Dec 11, 2013 by Kwaio  
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Nothing (by default).

Unless you are using some kind of encryption, every hop between your computer and the server you are accessing can read the packets you are transmitting and receiving.
answered Dec 11, 2013 by anonymous  
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In principle, "packet sniffing" is not a job of routers. Routers don't inspect the content of a packet, they just pick the header of the packet and find a suitable exit interface so that it will reach the destination stated in the packet's header.

However, your packets could be sniffed by anyone interested while the packets are moving. Interested bodies (often called attackers) can stop your packet and sniff it before it reaches the destination. This is called active sniffing, and is performed by firewalls. Another way of sniffing is passive sniffing. This method involves collecting copies of your packets passively. Wireless sniffing is a popular attack method in this category.

You can reduce such risks by using encryption techniques discussed above.
answered Dec 11, 2013 by anonymous  
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The real answer: Nothing you could do to prevent a router to sniff all of the traffic that flows through it. But that should not be the question - this should be: "What could I do to prevent anybody to read my traffic?" - The answer: "Use only encrypted communication/protocols!". The best thing: Use a VPN between you and your communication partner. For all others: HTTPS instead of HTTP, IMAPS instead of IMAP and so on.
answered Dec 11, 2013 by anonymous  
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As it was previously mentioned, it is not possible to stop a router from sniffing your data.

There is a simple way to make the listener's life harder by using Tor bundle.

Tor is a network of virtual tunnels that allows people and groups to improve their privacy and security on the Internet.

It cannot guarantee that your information will be 100% secure but if you use it properly (e.g Don't enable or install browser plugins), your data should be a bit more safe.

answered Dec 11, 2013 by anonymous