Hi, I'm trying to read IP packet headers manually from a hex file. From what I understand an IP header has 20 bytes: version, HL, TOS,total length, ID, flag, fragments,ttl, protocol, checksum, source ip and destination IP. In hex that would be something like this (20 bytes - double digits = 1 byte), A1 01 2C 1A being the source IP so the following 4 bytes is the destination ip means the end:

45 00 00 28 20 8F 40 00 80 06 00 00 A1 01 2C 1A BC D6 1D EF

but then i found a few that had more then 20 bytes as in the 20th byte was the last byte of the source IP but that wouldn't make sense coz in the IP stucture, the source IP is followed by destination IP meaning that the header found is 24 bytes instead of 20 bytes, like :

45 00 00 50 43 E8 00 00 40 06 5A DB 36 FB 98 DB A1 01 2C 1A 04 BA A4 D1

what does this mean? why is there extra bytes? even if the "option" field was to be counted in isn't it after destination ip address? Or is it possible for the source and destination address to switch places? meaning that the last 4 bytes is the source ip and the preceding 4 bytes is the destination ip?

*hope i explained things properly



I remember reading that there was a failure point on SSL as antiviruses were performing a MITM against browsers to verify the contents of connected pages. In practice they used to replace certificates in the client machine. Is this still an issue? See: http://ieeexplore.ieee.org/document/6956558/

Anyway, just a drop in the ocean.

Votes + Comments
AV vendors installing their own root certificates was always a recipe for disaster. I don't use AV products so I'm not really up to date on this

Additionally, in theory your ISP could inspect your data as it passes through them on its way to you. However, sites that contain important personal data (such as your bank, email provider, online shops you buy things from, etc) should be secured via SSL. This will prevent anyone from inspecting data in transit.

Your browser will tell you if a site is secure, just look for a green padlock on the left side of the URL bar.


It's a good idea not to send anything personal or important unless you can see one of these.


I am looking for advice about internet service providers. My questions here may seem silly but please do reply. I am an entrepreneur. I am about to start a new business. This business handles a lot of confidential documents and if any of these are leaked it could bring huge financial problems. So currently I am studying the ways my documents could be compromised and I have a few doubts.

Could there be a security breach through my ISP?
If yes, is there any way to prevent this?
How can prevent my data from being leaked?

I became paranoid about my data security after reading this article recently .Where ever I searched only news about American ISPs came up. I am using this business internet service provider in Canada. Do they have a history of leaking user data? Please advise on all this. Since I don't have any knowledge about Computer please explain in a non-geeky language.


Thanks, this is helpful. The system was setup by the Satellite people so I've no idea what was involved.

we usually point a web browser at the router, log in and configure.

Can you clarify what this means exactly? First, do I have to plug my wife's laptop directly into the router or can I access it through the homeplug system? Second, what webpage do I need to access? Third, I'm not aware of any log in information I've been given. Also do I need to download any software?

Thanks for your patience with a complete novice when it comes to networks.


You are right. There are few controls "on" the router. For control we usually point a web browser at the router, log in and configure.

The product manual is at https://www.linksys.com/us/support-product?pid=01t80000003KRTzAAO and small world, I have setup this model in the past.

Page 28 of http://downloads.linksys.com/downloads/userguide/E_Series_UG_E900Rev_3425-01486_Web.pdf notes the disabled feature.
Looks like you're all set.


My wife and I live in an area where Satellite Internet and Phone are the only option unfortunately. So our complex setup involves a modem, router and telephone adapter. My wife's health is such that she would like to remove the presence of WiFi signals in the house if possible. This isn't as ludicrous as it sounds. First, her laptop doesn't work with WiFi and my office (and desktop computer) are remote from the router so we work successfully with HomePlugs and don't actually need WiFi signals. My question is, is it possible somehow to remove the router and its WiFi signals from the system. There are three LAN cables that go into the back of the router, one from the phone adapter, one from the modem and one to the neaby HomePlug. I can't simply plug two of the cables into the modem even if that made sense, and I'm not sure it does, because the modem has only one LAN input. Thoughts please.