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@Calgary

check this as well...

redspider(忙啥！歇着吧！)
Another possibility is ident. Some servers use ident for reverse lookups. If ident is being dropped at the firewall, this will cause a delay. You can shorten this delay by adding a rule to reject ident (as opposed to drop), which will time ident out much quicker.

You can turn that off by modifying /etc/xinetd.d/telnet and commenting out the line that reads:

log_on_failure += USERID

If ident is the problem the telnet connections will establish quickly and you'll get a logon prompt after at most 30-40 seconds (DNS lookup delay). If that solves the problem we'll have to look at how to turn off ident for the other services.
(#1246763@0)
Last Updated: 2003-6-18
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Replies, comments and Discussions:

  • 工作学习 / IT技术讨论 / 2个网络的怪问题 -oceandeep(北极熊·夜半歌声); 2003-6-17 {291} (#1245947@0)
    1、一台服务器，如果PING，一点问题没有，很快，从TELNET过去开始，到出现LOGIN，要很长时间（大概5-10分钟），但出现LOGIN后又正常了

    2、另外一台，PING也是好的，但如果用FTP传文件，传到一部分后，就停止了，进程还在，但数据传输好象几乎停止了，尝试用RCP或者UUCP都一样。

    注：以上服务器都是LINUX系统
    • can't figure out anything form you post, but -eagle_no1(瞎起哄); 2003-6-17 {141} (#1245964@0)
      you can download a software called "ethreal" from gnu and intercept the packet form the network, you will be easy to figure out what happen
      • 我有空试试，你觉得大概是什么问题？ -oceandeep(北极熊·夜半歌声); 2003-6-17 (#1246047@0)
        • who knows? maybe something regarding TCP or TCP connection establishment -eagle_no1(瞎起哄); 2003-6-18 (#1246119@0)
    • enable dns or edit /etc/host file. -songl(我爱春天,我爱阳光); 2003-6-17 (#1246070@0)
      • 不觉得这两个文件有问题啊，站点地址都在HOSTS文件里面 -oceandeep(北极熊·夜半歌声); 2003-6-18 (#1246074@0)
        • the above suggestion deos makes sense. did you telnet ip address or machine name?? go ahead and try both -eagle_no1(瞎起哄); 2003-6-18 (#1246135@0)
          • 应该试过了，那时候估计快疯了，啥都试过了 -oceandeep(北极熊·夜半歌声); 2003-6-18 (#1246271@0)
        • bear in mind, telnetd is trying reverse name lookup. -songl(我爱春天,我爱阳光); 2003-6-18 (#1246181@0)
          • 双方的hosts文件都是完整的 -oceandeep(北极熊·夜半歌声); 2003-6-18 (#1246272@0)
            • make sure you using hosts before dns if you don't have dns setup correctly. (e.g nsswitch.conf) -openvision(子鱼非我鱼); 2003-6-18 (#1246901@0)
    • this could help... -redspider(忙啥！歇着吧！); 2003-6-18 {397} (#1246755@0)
      This sounds like a reverse DNS lookup. Make entries in '/etc/hosts' for each machine. You should also have the line "order hosts, bind" in '/etc/host.conf' .

      check ifconfig for the info about RX errors and TX overruns, if they have large number of error, that could be a symptom of poor interrupt handling in the kernel of hardware.

      try use another NIC, see if the speed is improved...
      • check this as well... -redspider(忙啥！歇着吧！); 2003-6-18 {639} (#1246763@0)
        Another possibility is ident. Some servers use ident for reverse lookups. If ident is being dropped at the firewall, this will cause a delay. You can shorten this delay by adding a rule to reject ident (as opposed to drop), which will time ident out much quicker.

        You can turn that off by modifying /etc/xinetd.d/telnet and commenting out the line that reads:

        log_on_failure += USERID

        If ident is the problem the telnet connections will establish quickly and you'll get a logon prompt after at most 30-40 seconds (DNS lookup delay). If that solves the problem we'll have to look at how to turn off ident for the other services.

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