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The Internet

Longest Open TCP Connection? 37

Posted by Cliff from the does-Guiness-know-about-this-yet? dept.
I thought it would be fun to run this submission fromivan256 who asks: "I was sitting at my desk noticing that i had be telneted between my linux boxes for 16 days, and it got me wondering... What would be the longest continuously open TCP connection? Is it still open?" I'd highly doubt this has actually been recorded, but I'm sure you guys have personal records you wouldn't mind bragging about.
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Longest Open TCP Connection? More

Longest Open TCP Connection?

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  • Some hard core mudders over the years would have pushed limits of endurance. The only limit to the open time is mud reboots.
  • Do dumb terminals count? The x-term's server at my school is rebooted something like twice a year and since each of the "millions" of dambed x-terms use tcp for status and loging.....

    At home I have kept a telnet session open for 2 weeks.... being used about 6 of 24 hours...

    Well tis my 2 cents...
    (even less with exchange)
  • I'd guess the longest open connection would be on a trading system that's been constantly up for years, for example at an investment bank.
  • I have seen IRC "idling" competitions hit months. Most of these people are either A> On the local machine. or B> On the local ethernet. But it's still over TCP/IP. These competitions could get crazy if there was such a thing. Think about it. You might have some sort a database over a ethernet on TCP/IP that has been open for two years or something like that.

  • Routing protocols (Score:1)

    by Anonymous Coward
    BGP runs over TCP. There are probably some routers that have been up a while.
  • I personally recorded over 2000 hours, which is like 3 months. It was a telnet session between one host on my network to another running a modified telnetd to take the user directly into a BBS program. No crash, no reboots, nothing. until that one day I hit ctrl-alt-del on the wrong keyboard and felt like a dumbass.
    Anyway, it was a fun record to set, still got people attempting to duplicate it.

  • Heh... (Score:1)

    by Guyle ( 79593 )
    And I thought my 62-hour record connection to an ISP I used to be with was good... heheh... staying connected to them was a pain in the rear.

    Anyway, I tend to agree with the financial institution notion - they have to keep things open so us people can make our transactions 24/7. Although I have met a few people on IRC who would tend to push that record a bit... hehe.
  • BGP uses TCP, but the connections between routers are not constant, they connect periodically to exchange information, mostly routing table updates and to let their neighbors know they're still alive. Besides, open TCP connections are expensive, a router has better things to do most of the time.

  • More importantly... (Score:1)

    by Anonymous Coward
    Who has had the longest open UDP connection? Snicker.
  • If you found an ATM (Automatic Teller Machine) that hadn't broken for quite a while (hard to find perhaps, but they must exist), I don't know if they use TCP/IP, it's more likely some custom hypersecure protocol designed for low numbers of clients, but they stay open 24/7, and they've been around for a long time.

  • icewm (Score:1)

    by Trojan ( 37530 )
    NT that I have to use at work is getting to me as well. A few days ago I accidentally hit ctrl-alt-del on my Linux box at home, and much to my surprise it was caught by icewm. Still not sure if this is entirely a good thing, but I guess for me it's too late to complain.
  • The ATM normally are using X.25 connection.
    They open a VC with an host system ant the link
    stays open until the ATM goes in maintenace, or
    the link hangs up.
    ATM normally are using SNA derivatives.

    So the VC could be up for days because is taxed
    on a packet by packet basis, and even if is only @
    4800 bps, is totally sufficient for ATMS.



  • Having worked in the backbones of a bank or two, I can say that trading floors seem to go up and down like a yo-yo.

    Mainly because of the amount of 56k lines to branches and all the legacy X.25 stuff that's been sitting sucking dust in its fans forever!

    mindslip
  • i use screen to telnet to a chat daemon on localhost. so long as the chat stays up, there's a port open. :)

  • I presently have a little work horse of a webserver that I use for some of my original clients. It's been up for 344 days solid now. It would have been up longer, but I had to move it from one room to another less then a year ago.

    Is there any sort of record for the longest uptime of a *NIX box?

  • We had a production server that was up for 497 days, 2 hours, and 27 seconds before crashing itself about a week ago. Apparently the version of the Linux kernel it was running wasn't able to handle the "jiffy roll" problem -- sort of a little mini Y2K where the jiffy timer counter in the kernel overflows its 32 bits. At that point, two processes (cron and some at job) started spawning violently and brought the load average up to about 15, when it promptly died from a disk controller problem ;-).

    Before that, we were afraid to reboot the thing because we didn't know if it would come back up right, and it's been up for so long that it's been up longer than I've been with the company. It still had an early version of Debian 2.0 with kernel 2.0.35 =). We were planning to run its UPS down to my car and plug it into a power inverter to get it somewhere without shutting it down, but alas, that isn't neccessary now. ='| =)
  • Could someone maybe open a loopback connection and keep it open for eternity? Just run Linux with *no* processes (sp?) open except the necessary ones, a server, and a client. With nothing to get in the way, could this connection last until Armageddon?
  • Speaking of dust, why can't someone come up with cases with single air inlet that you can slide replacable HEPA filter cartridges into? Protect your equipment and clean the air in the room.

  • Do UNIX-TCP-sockets count or just TCP/IP?
    LINUX stands for: Linux Inux Nux Ux X

  • Am I right in thinking that in theory a TCP connection could remain open indefinitely but that all TCP connections are limited to a maximum amount of data that they can transfer? Something to do with the fact that a byte count of fixed length is contained in each packet.

    This makes the original question rather academic; You can leave a connection open as long as you want but you cannot send any data over it in case you go over the limit...

  • Nope.

    TCP contains sequence numbers, which are incremented by the number of octets in the packet. This is used as part of the recovery from lost or duplicated packets, but they start at a 'random' number, and it's normal for them to roll over, so you can transmit an infinite number of bytes over the same connection.

    There is a time frame where the same sequence number shouldn't be reused, so that gives an limit on the number of bytes which can be transmitted in a single time period (2GB/2 hours seems to ring a bell with me), but if it's slower than that, then you can go on forever.

  • Well, what I consider a personal record occured about 10 years back. Internet connections abroad were flaky at best, and totally unreliable usually.

    It must have been in late 1989 or early 1990 when I held a connection open from Delft, the Netherlands to IscaBBS in Iowa City for 6:52, which was an amazing feat at the time. However, by the end of the session the Americans were up and going to work/school so the routers got loaded and the connection failed.

    Ah, those times....

  • As a Webhosting company I've got two telnet sessions in NT open to the two Linux boxes we use for dns1 and dns2. I use them 2-3 times a day to check the status of Linux and add/delete zone information. I've had them connected since I booted the machines, 312 days agu. This also means I've had NT workstation running for 312 days without crashing it.
  • This would be the best contest. I once kept a connecting to my ISP for 73 1/2 hours. I was doing FTP downloads and IRC idling.
  • I dont know, but the historic directory on kernel ftp sites really tempt me with that 0.01 kernel. I will boot that kernel someday, and all shall worship my coolness. :)
  • As I work for a large business information company, we provide global access dial-up for various web and FTP based products, I've seen quite a few 'long' ISDN phone calls - i.e. several weeks long!!!! As for TCP connections, we have machines that have uptimes easily in the hundreds of days.
  • Technically that wouldn't be TCP, right? A loopback connection doesn't actually go over any network unless for some reason you made it do that.
  • Don't kick me for mentioning MS, but i have to say that MSN was the best Dialup ISP for me. Sometimes i had 1 to 3 days connections, and once i had 5 days and 3 hours. PS. Don't mention that, i know that MSN is hosted by UU.net :)

  • We're not worthy... ;-)

    In the immortal words of the little green aliens in Toy Story....iiiieeeeeeeeewwwww...

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