Re: FTP hangs, taking 100% CPU
On Mon, Mar 12, 2001, Aviram Jenik wrote about "FTP hangs, taking 100% CPU": It can even continue to 'run' for days, even though the FTP client is long gone. What's worse, it takes 100% CPU, and if a second connection is initiated, a second process remains with an additional 100% CPU (and this really takes the fun out of our 2 CPU machine). The whole thing is very strange, since there's no problem with any FTP clients besides this one, and there's nothing special about our FTP daemon (wu-ftpd-2.6.0). Does anybody have a clue about what might be causing this? I've seen this happen on an FTP server that runs (among other things) ftp.ivrix.org.il. It is running wu-ftpd-2.6.1(2), and roughly once in two weeks an FTP process hangs like you describe, wasting CPU until I kill it. I could never find out what is causing this, or when it happens (I didn't notice what kind of client causes this, because ftp doesn't have a user-agent capability like HTTP). I never saw this problem in the previous version I had installed (2.6.0), but maybe it's just a coincidence - it certainly looks like the same problem you describe. It's quite likely an wu-ftpd bug - now that you know how to recreate the problem (I never could), perhaps you should file a bug report with wu-ftpd? (or debug it yourself!). No matter how buggy or misbehaving a client is (if it is at all), it shouldn't cause the server to hang in a tight loop, because that is a denial-of-service risk. -- Nadav Har'El| Tuesday, Mar 13 2001, 18 Adar 5761 [EMAIL PROTECTED] |- Phone: +972-53-245868, ICQ 13349191 |The socks in my drawer are like http://nadav.harel.org.il |snowflakes: No two are alike. = To unsubscribe, send mail to [EMAIL PROTECTED] with the word "unsubscribe" in the message body, e.g., run the command echo unsubscribe | mail [EMAIL PROTECTED]
Re: FTP hangs, taking 100% CPU
On Mon, 12 Mar 2001, Aviram Jenik wrote: There's a problem that's been driving us crazy for a while here. One of our users connects using explorer as an FTP client. I'm not sure whether or not Explorer does an explicit disconnect when the window is closed, but in any case, after the FTP session is done, the process in.ftpd remains 'alive' until it's killed manually. It can even continue to 'run' for days, even though the FTP client is long gone. What's worse, it takes 100% CPU, and if a second connection is initiated, a second process remains with an additional 100% CPU (and this really takes the fun out of our 2 CPU machine). The whole thing is very strange, since there's no problem with any FTP clients besides this one, and there's nothing special about our FTP daemon (wu-ftpd-2.6.0). Does anybody have a clue about what might be causing this? 1. What is the output of netstat -a on both the client and the server ? 2. strace is your friend. 3. Upgrade your ftpd. - Aviram = To unsubscribe, send mail to [EMAIL PROTECTED] with the word "unsubscribe" in the message body, e.g., run the command echo unsubscribe | mail [EMAIL PROTECTED] -- Yaron. = To unsubscribe, send mail to [EMAIL PROTECTED] with the word "unsubscribe" in the message body, e.g., run the command echo unsubscribe | mail [EMAIL PROTECTED]
Re: FTP hangs, taking 100% CPU
On Tue, Mar 13, 2001, Yaron Zabary wrote about "Re: FTP hangs, taking 100% CPU": 3. Upgrade your ftpd. You can try it (and you SHOULD do it because of the security holes in the unpatched version 2.6.0!), but as I said 2.6.1(2) still gives me a problem which appears similar, so maybe upgrading won't solve the problem. But it is sure worth trying. -- Nadav Har'El| Tuesday, Mar 13 2001, 18 Adar 5761 [EMAIL PROTECTED] |- Phone: +972-53-245868, ICQ 13349191 |You have the right to remain silent. http://nadav.harel.org.il |Anything you say will be used against you. = To unsubscribe, send mail to [EMAIL PROTECTED] with the word "unsubscribe" in the message body, e.g., run the command echo unsubscribe | mail [EMAIL PROTECTED]
Re: FTP hangs, taking 100% CPU
On Mon, Mar 12, 2001 at 11:29:57PM +0200, Aviram Jenik wrote: There's a problem that's been driving us crazy for a while here. One of our users connects using explorer as an FTP client. I'm not sure whether or not Explorer does an explicit disconnect when the window is closed, but in any case, after the FTP session is done, the process in.ftpd remains 'alive' until it's killed manually. It can even continue to 'run' for days, even though the FTP client is long gone. What's worse, it takes 100% CPU, and if a second connection is initiated, a second process remains with an additional 100% CPU (and this really takes the fun out of our 2 CPU machine). The whole thing is very strange, since there's no problem with any FTP clients besides this one, and there's nothing special about our FTP daemon (wu-ftpd-2.6.0). Does anybody have a clue about what might be causing this? First of all Wu-FTPD is so full of security holes it's not even funny. Now, what does an strace of these processes show? = To unsubscribe, send mail to [EMAIL PROTECTED] with the word "unsubscribe" in the message body, e.g., run the command echo unsubscribe | mail [EMAIL PROTECTED]
Re: FTP hangs, taking 100% CPU
Hello Aviram First, you'd better use proftpd ... less bugs :) Anyway, in my proftpd there's a way to set the maximum idle time, so after X minutes it'll close itself automatticly. probably in wuftpd too. About the cpu, I have no idea. Cya, Oren. On Mon, 12 Mar 2001, Aviram Jenik wrote: There's a problem that's been driving us crazy for a while here. One of our users connects using explorer as an FTP client. I'm not sure whether or not Explorer does an explicit disconnect when the window is closed, but in any case, after the FTP session is done, the process in.ftpd remains 'alive' until it's killed manually. It can even continue to 'run' for days, even though the FTP client is long gone. What's worse, it takes 100% CPU, and if a second connection is initiated, a second process remains with an additional 100% CPU (and this really takes the fun out of our 2 CPU machine). The whole thing is very strange, since there's no problem with any FTP clients besides this one, and there's nothing special about our FTP daemon (wu-ftpd-2.6.0). Does anybody have a clue about what might be causing this? - Aviram = To unsubscribe, send mail to [EMAIL PROTECTED] with the word "unsubscribe" in the message body, e.g., run the command echo unsubscribe | mail [EMAIL PROTECTED] = To unsubscribe, send mail to [EMAIL PROTECTED] with the word "unsubscribe" in the message body, e.g., run the command echo unsubscribe | mail [EMAIL PROTECTED]
