tcp_keepalive_probes : Number of KEEPALIVE probes tcp sends out, until the server decides that the connection is broken.
tcp_keepalive_time : This value shows how often tcp sends out KEEPALIVE messages. The default is 7200 (2 hours).
tcp_syn_retries : Number of times initial SYNs for a TCP connection attempt will be retransmitted. This value should not be more than 255. This is only the timeout for outgoing connections.
tcp_retries1 : This defines how often an answer to a TCP connection request is retransmitted before it gives up. This is only the timeout for incoming connections.
tcp_fin_timeout : The length of time (in seconds) TCP takes to receive a final FIN before the socket is always closed. This is required to prevent DoS attacks
You can change the values by updating the files in /proc/sys/net/ipv4 or sysctl . To make it permanent add it to /etc/sysctl.conf. Below are the default values of these parameters, you can change these values to suite your requirement.
# vi /etc/sysctl
net.ipv4.tcp_fin_timeout = 60
net.ipv4.tcp_retries1 = 3
net.ipv4.tcp_keepalive_probes = 9
net.ipv4.tcp_keepalive_time = 7200
net.ipv4.tcp_syn_retries = 5
#
Free, facebook, tips, Links, blogging, Downloads, Google, facebookTips, money, news, apps, Social, Media, Website, Tricks, games, Android, software, PIctures, Internet, Security, Web, codes, Review, bloggers, SAMSUNG, Worldwide, Contest, Exitic, Phones, facebookTricks, hacking, London, Olympics, SEO, Youtube, iOS, Adsense, gadgets, iPHONE, widgets, Doodle, twitter, video, Deals, technology, Aircel, Airtel, iPAD, Angry, Birds, BSNL, TechLife, GMAIL, Idea, Microsoft, SmartPhones, Stress, Buster, Windows, Yahoo, Infolinks, Nokia, Scam, Uninor, browsers, Amazon, Euro, CUP, Chat, IDM, JOBS, Modem, Music, Reliance, Results, SSC, Tata, Docomo, bing, freebie, mobile, placements, AIEEE, AlertPay, Chrome, College, Competetive, Exam, Dehradun, Extension, FireFox, GPRS, HTC, IMPACT, Info, MTS, Mark, Zukerberg, Paypal, Promotional, Post, Torrent, UTU, Unlocking, VodaFone, Wall, Paper, apple, books, engineering, iCAR, iTunes, pinterest, rovio, AVG, Admit, Card, Adobe, Affiliate, Marketing, Akhilesh, Amul, Girl, BlackBerry, ChromeBook, Clixsense, Coupon, Digitallife, Discovery, Emoticons, Festival, GATE, GIMP, Income, Tax, International, JSS, JailBreaking, Kindle, Linux, Local, MAX, PAYNE, Mac, Mango, Memory, Speed, Nexus, Online, Shopping, Raakhi, Report, Rising, Stars, Sample, Science, Sony, Syllabus, TabletBooK, Teamviewer, Templates, Dark, Knight, Rises, USA, UPMT, Virgin, Xperia, ZTE, challan, counselling, course, btech, funny, iMOVE, registration
source:http://linuxpoison.blogspot.com/2008/09/13578175713637.html