Uthman ibn Affan spelled by the Turkish and Persian rendering Osman, was a son-in-law and notable companion of the Islamic prophet Muhammad, as well as the third of the Rashidun, or "Rightly Guided Caliphs". Born into a prominent Meccan clan, Banu Umayya of the Quraysh tribe, he played a major role in early Islamic history, is known for having ordered the compilation of the standard version of the Quran; when Caliph Umar ibn al-Khattab died in office aged 59/60 years, aged 64/65 years, succeeded him and was the second-oldest to rule as Caliph. Under Uthman's leadership, the Islamic empire expanded into Fars in 650, some areas of Khorasan in 651; the conquest of Armenia had begun by the 640s. His reign saw widespread protests and unrest that led to armed revolt and his assassination. According to Sunni and Shia belief, Uthman was married to Ruqayyah, upon her death, married Umm Kulthum. Both his wives having been elder daughters of Muhammad and Khadija earned him the honorific title Dhū al-Nurayn.

Thus, he was brother-in-law of the fourth Rashidun Caliph Ali whose own wife, was Muhammad's youngest daughter. Uthman was born to Affan ibn Abi al-'As, of the Umayya, to Arwa bint Kurayz, of the Abdshams, both wealthy clans of the Quraysh tribe in Mecca. Arwa's mother was Umm Hakim bint Abdul Muttalib, making Arwa the first cousin of Muhammad and Uthman his first cousin's son. Uthman had Amina. Uthman was born in Ta'if; the exact date is disputed: both 576 and 583 are indicated. He is listed as one of the 22 Meccans "at the dawn of Islam", his father, died at a young age while travelling abroad, leaving Uthman with a large inheritance. He became a merchant like his father, his business flourished, making him one of the richest men among the Quraysh. On returning from a business trip to Syria in 611, Uthman learned of Muhammad's declared mission. After a discussion with Abu Bakr, Uthman decided to convert to Islam, Abu Bakr brought him to Muhammad to declare his faith. Uthman thus became one of the earliest converts to Islam, following Ali, Abu Bakr and a few others.

His conversion to Islam angered his clan, the Banu Ummayyah, who opposed Muhammad's teachings. Uthman and his wife, migrated to Abyssinia in April 615, along with ten Muslim men and three women. Scores of Muslims joined them later; as Uthman had some business contacts in Abyssinia, he continued to practice his profession as a trader and he continued to flourish. After four years, the news spread among the Muslims in Abyssinia that the Quraysh of Mecca had accepted Islam, this acceptance persuaded Uthman, Ruqayya and 39 Muslims to return. However, when they reached Mecca, they found that the news about the Quraysh's acceptance of Islam was false. Uthman and Ruqayya re-settled in Mecca. Uthman had to start his business afresh, but the contacts that he had established in Abyssinia worked in his favour and his business prospered once again. In 622, Uthman and his wife, were among the third group of Muslims to migrate to Medina. Upon arrival, Uthman stayed with Abu Talha ibn Thabit before moving into the house he purchased a short time later.

Uthman was one of the richest merchants of Mecca, with no need of financial help from his Ansari brothers, as he had brought the considerable fortune he had amassed with him to Medina. Most Muslims of Medina were farmers with little interest in trade, Jews had conducted most trading in the town. Uthman realized there was a considerable commercial opportunity to promote trade among Muslims and soon established himself as a trader in Medina. With hard work and honesty, his business flourished; when Ali married Fatimah, Uthman bought Ali's shield for five hundred dirhams. Four hundred was set aside as mahr for Fatimah's marriage. Uthman presented the armour back to Ali as a wedding present. According to R. V. C. Bodley, during Muhammad's lifetime, Uthman was not an outstanding figure, was not assigned to any authority, earned no distinction in any of Muhammad's campaigns. Uthman had a reputation of favouring family members. One way he displayed this was his habit of splitting war booty among his relatives to the exclusion of the combatants.

During the Invasion of Hamra al-Asad a Meccan spy, Muawiyah bin Al Mugheerah, the cousin of Uthman ibn Affan, had been captured. According to the Muslim scholar Safiur Rahman Mubarakpuri, Uthman gave him shelter after getting permission from Muhammad, Muhammad told him that if he was caught again after 3 days he would be executed; as such, Muawiyah was given a grace period of three days and arranged a camel and provisions for his return journey to Mecca. Uthman departed with Muhammad for Hamra-al-Asad, Muawiyah overstayed his grace. Though he fled by the time the army returned, Muhammad ordered his execution; the orders were carried out. In 632, the year Muhammad died, Uthman participated in the Farewell Pilgrimage. Uthman was present at the event of Ghadir Khumm, according to Shia sources, he was among those who pledged allegiance to Ali. Uthman had a close relationship with Abu Bakr, as it was due to him that Uthman had converted to Islam; when Abu Bakr was selected as the caliph, Uthman was the first person after Umar to offer his allegiance.

During the Ridda wars, Uthman remained in Medina. On his deathbed, Abu Bakr dictated his will to Uthman. Umar, on his deathbed formed a committe

A keepalive is a message sent by one device to another to check that the link between the two is operating, or to prevent the link from being broken. A keepalive signal is sent at predefined intervals, plays an important role on the Internet. After a signal is sent, if no reply is received the link is assumed to be down and future data will be routed via another path until the link is up again. A keepalive signal can be used to indicate to Internet infrastructure that the connection should be preserved. Without a keepalive signal, intermediate NAT-enabled routers can drop the connection after timeout. Since the only purpose is to find links that don't work or to indicate connections that should be preserved, keepalive messages tend to be short and not take much bandwidth. However, their precise format and usage terms depend on the communication protocol. Transmission Control Protocol keepalives are an optional feature, if included must default to off; the keepalive packet contains no data. In an Ethernet network, this results in frames of minimum size.

There are three parameters related to keepalive: Keepalive time is the duration between two keepalive transmissions in idle condition. TCP keepalive period by default is set to no less than 2 hours. Keepalive interval is the duration between two successive keepalive retransmissions, if acknowledgement to the previous keepalive transmission is not received. Keepalive retry is the number of retransmissions to be carried out before declaring that remote end is not availableWhen two hosts are connected over a network via TCP/IP, TCP Keepalive Packets can be used to determine if the connection is still valid, terminate it if needed. Most hosts that support TCP support TCP Keepalive; each host periodically sends a TCP packet to its peer. If a certain number of keepalives are sent and no response is received the sending host will terminate the connection from its end. If a connection has been terminated due to a TCP Keepalive time-out and the other host sends a packet for the old connection, the host that terminated the connection will send a packet with the RST flag set to signal the other host that the old connection is no longer active.

This will force the other host to terminate its end of the connection so a new connection can be established. TCP Keepalives are sent every 45 or 60 seconds on an idle TCP connection, the connection is dropped after 3 sequential ACKs are missed; this varies by host, e.g. by default Windows PCs send the first TCP Keepalive packet after 7200000ms sends 5 Keepalives at 1000ms intervals, dropping the connection if there is no response to any of the Keepalive packets. Since TCP keepalive is optional, various protocols implement their own keep-alive feature on top of TCP, it is common for protocols which maintain a session over a connectionless protocol, e.g. OpenVPN over UDP, to implement their own keep-alive; the Hypertext Transfer Protocol uses the keyword "Keep-Alive" in the "Connection" header to signal that the connection should be kept open for further messages. Despite the similar name, this function is unrelated. "Keep-alive" devices are used in automotive repair to maintain battery voltage for devices in the vehicle when the battery is disconnected or changed by plugging in a small battery to the vehicle's 12 volt power outlet.

A typical application is preventing the vehicle's radio or other device from going to "code" mode during vehicle repair. A lower voltage source, such as a 9–volt battery, is sufficient for the purpose. Electric clocks have battery-powered keep-alive circuits to maintain time and other settings during a power outage; some electronic devices use a capacitor circuit to maintain volatile memory when the user changes the battery. Switch Watchdog timer Hole punching UDP hole punching

Marcos Ligero, better known as D-Mark, is a Spanish Electronic Dance Music DJ, musician and producer. Starting with the music as a hobby in the late 90s and at the early age of 13 he became an enthusiast of the dance music genre of the moment, passed to be a mere follower to become a producer before starting his career as a DJ. D-Mark begun in the field of the music production using a tracker production software that were available in the moment for his pretty old computer. So much he liked this, that drove him to lead a -now disappeared- project called Vanian-UT, which the only aim was to spread all of these tracks made with that software across all the Spanish territory. What started to be a project charged of illusion, soon would become in a truth that exceeded all the expectations. In 2002, Vanian-UT was known in Spain as a young producers' collective with a lot of talent, that began forcely focused to the DJing, something that caught the attention of D-Mark as well; this year, Vanian-UT released with D-Mark mixes a set of CDs for the now disappeared magazine Solo Tuning.

Year 2003 was a new begin for D-Mark. Focused on his DJ side and with the Vanian-UT project running at its top, the collective begun to perform their music on several clubs and events in the zone, like regular parties at Future Club in Barcelona or the event Trancenight Summer Party at Girona in 2004. 2005 was a year of changes. As new systems and computer production software became more affordable to everyone and the record deals were increasing into its members Vanian-UT was about to close, what took D-Mark to initiate and lead a new record label project called DanceDP Recordings; this idea was set up this year, but it would not come to light until the end of 2006. Meanwhile, D-Mark took his first appearance outside the zone of Catalunya and moved to Madrid to perform a gig alongside DJ Precision and Menno de Jong, together with his friends and artists Shammu, DJ Row and the resident DJ at Future Club in Barcelona Pllo Future. 2006 and 2007 were, without a doubt, musical career of D-Mark. During this time, he carried his music through all the Spanish territory in the cities of Ibiza, Madrid or Valladolid, the countries of Norway and Slovenia and performing together with some of the most influenced DJs of the dance scene at these years, like Above & Beyond, Lemon & Einar K or Inkfish.

In 2006 he made his debut abroad, in a Ministry of Sound event at Sentrum Scene in the city of Oslo, Norway. These years were when D-Mark set the opening of his new record label project DanceDP Recordings; the first release of the record label and the first appearance of D-Mark in the music industry as well, Travelling EP, became unexpectedly a success: 10 weeks in a row at the top positions of the Technics/IDP/DMC Dutch Dance Charts and full reviews on the Spanish magazines Deejay and DJ1, that ended with the DJ Oner award No. 1 Spanish trance release and the appearance of Project Norway in the album of Dave Pearce Delirium on the label Ministry of Sound. In 2007 and 2008 D-Mark teamed up with who would be now his best friend in the music field and his studio and DJ partner G-Sus, they two together released several remixes for artists like Tragida and Der Mystik, their hit La Lamida del Gato Negro produced in 2008 and released in 2009 got the unexpected support of the world's top DJ Paul van Dyk. 2008 is the starting year of D-Mark's monthly radio/podcast project DanceDP Radio.

The project begun with the appearances and the support of Raúl CC and David Amante the first year, until David left his music career. G-Sus joined the team in 2010, where he is an active part of the show. 2009 and 2010 were two difficult years to the personal life of D-Mark that forced him to stop the recording of his announced album debut Driving Nowhere and to leave momentarily his musical activity, affecting his record label. The album was discarded due to the crisis, passing through the music industry in Spain, the world's economy. However, this did not stop D-Mark and G-Sus in 2009 to organize and perform a special event in Pineda de Mar, the one who had the biggest attendance for them of all the times in Spain, 5500 attendees. 2011 is the year, as he said, of the coming back, with a new EP release and an amateur official videoclip made for what is his favourite city, Barcelona. 2011: Physical Phase – Inception 2011: Barcelona EP including Barcelona, Surfing the Waves and I See The Light 2011: Edu NRG – Return Flight 2010: Chimo Bayo – La Fiesta del Fuego 2009: La Lamida del Gato Negro ft. G-Sus, incl.

Desired Melody 2008: Tomahawk 2007: Jaco & Mixxmaster – Feeling 2007: Tragida – The Milky Land 2007: Angel Ace – Finally 2007: KOS Project – My World 2007: Tragida – My Pinky Lady 2006: Travelling EP including Travelling, That's Cool and Project Norway 2006: DJ Nash – Life is not a Dream 2010: Linkin Park – The Catalyst – MySpace Contest 2009: Der Mystik – Tuxedo – Due to record label closing 2008: Trance Claschen – One for Me 2007: Emotional Horizons – Lush 2010: Ibiza Trance Anthems 2010 with Chimo Bayo – La Fiesta del Fuego 2010: Pumping Trance Vol.4 with D-Mark feat. G-Sus – Desired Melody 2009: 50 Ultimate Trance Classics with Angel Ace – Finally 2008: We Create a Mental Atmosphere with Tragida – My Pinky Lady 2007: Tr