Save some bandwidth by turning off TCP Timestamps

This is a guest post by Donatas Abraitis, System Engineer at Vinted, with an unusual approach for saving a little bandwidth.

Looking at https://tools.ietf.org/html/rfc1323 there is a nice title: 'TCP Extensions for High Performance'. It's worth to take a look at date May 1992. Timestamps option may appear in any data or ACK segment, adding 12 bytes to the 20-byte TCP header. 

Using TCP options, the sender places a timestamp in each data segment, and the receiver reflects these timestamps back in ACK segments. Then a single subtract gives the sender an accurate RTT measurement for every ACK segment.

To prove this let's dig into kernel source:

./include/net/tcp.h:#define TCPOLEN_TSTAMP_ALIGNED    12
./net/ipv4/tcp_output.c:static void tcp_connect_init(struct sock *sk)
  ...
  tp->tcp_header_len = sizeof(struct tcphdr) +
    (sysctl_tcp_timestamps ? TCPOLEN_TSTAMP_ALIGNED : 0);

Some visualizations:

Worth Reading: Digital Content and the Fate of Businesses

There are two key differences between buying media in a physical format versus a digital one. First, there’s the technical aspect: Maintaining long-term access to a file requires a hard copy of it—that means, for example, downloading a film, not just streaming from a third party’s server. The second distinction is a bit more complicated, and it has to do with how the law has shaped digital rights in the past 15 years. It helps to think about the experience of a person giving up CDs and using iTunes for music purchases instead. —via the atlantic

Continue reading

9 ways to celebrate “Back to the Future” Day

Another made up geeky dayWednesday, Oct. 21, 2015 marks the day in which time-traveler Marty McFly arrives from the past (from the movie “Back to the Future Part II”. The Internet is freaking out about this upcoming “holiday”, and in the tradition of fake geeky holidays like “Star Wars Day” (May 4), Pi Day (March 14) and “Talk like a Pirate Day” (September 19), we now have a day to celebrate everything related to the time-travel movie, which is celebrating its 30th anniversary this year.To read this article in full or to leave a comment, please click here

Magento database tool Magmi has a zero-day vulnerability

An open-source tool for importing content into the Magento e-commerce platform, called Magmi, has a zero-day vulnerability, according to security vendor Trustwave. The directory traversal flaw is in some versions of Magmi, which is used to move large amounts of data into Magento's SQL database. Such a flaw can allow access to other files or directories in a file system. "Successful exploitation results in access to Magento site credentials and the encryption key for the database," wrote Assi Barak, lead security researcher with Trustwave's SpiderLabs.To read this article in full or to leave a comment, please click here

US, UK disrupt Dridex botnet, which targeted online banking

A cybercriminal network that caused at least US$10 million in losses has been disrupted by U.S. and U.K. law enforcement, with the U.S. seeking a Moldovan man's extradition, the Department of Justice said Tuesday.Andrey Ghinkul, 30, is accused of being the administrator of the Dridex botnet, also known as Cridex and Bugat.A nine-count indictment was unsealed on Tuesday in the U.S. District Court for the Western District of Pennsylvania,  DOJ said. Ghinkul was arrested on Aug. 28 in Cyprus.Dridex has been a real headache for a number of years. It collects online banking credentials from infected computers, which prosecutors said were then used to initiate large wire transfers.To read this article in full or to leave a comment, please click here

Phishing websites look more legit with SSL certs from major companies

The Web is full of deception, and it's sometimes still hard for people to figure out if the website they're viewing really is what it says it is.This type of cyberattack, known as phishing, is designed to elicit sensitive details from victims by creating websites that look nearly identical to services like PayPal or Bank of America.Despite improvements in quickly detecting and taking such sites offline, it's still a huge problem.A U.K.-based network monitoring company, Netcraft, says fraudsters are exploiting weaknesses in technology companies in order to make more convincing looking phishing sites.Many websites use SSL/TLS (Secure Sockets Layer/Transport Layer Security) certificates to verify their domain name and encrypt communications with users.To read this article in full or to leave a comment, please click here

1 … 3,253 3,254 3,255 3,256 3,257 … 3,809