I have a complex network setup on a RedHat 7.0 linux box. I am trying to
troubleshoot a Very Slow Linux FTP Server. The wu-ftpd 2.6 server on my
linux box is not serving up files faster than 64 kb/s, and only works if I
use an FTP client where I can force a limit to throughput of 64 kb/s or
less. If I use the command line FTP client, I can't get files to transfer at
I have a Windows 2000 network client using LeechFTP, a nice FTP Client for
windows, that allows you to throttle your FTP download speed to a maximum of
say, 16 kb/s. If I set that limit before I start a download, of 16 kb/s,
then the download will proceed at a steady pace, at 16 kb/s. If I set the
limit to 64 kb/s, it proceeds at 64 kb/s. If I remove the limit altogether,
the file transfer stops. This weird behaviour only applies to my local
Linux box. Any downloads through the Linux box out to the internet, via IP
Masquerading, are working just fine. FTP from my windows client machine out
through linux IP masquerading, to an Internet FTP host like ftp.cdrom.com,
regularly exceeds 100 kb/s in speed, and has no problems.
It's only from my local LAN Client (Windows 2000) to my local LAN server
(RedHat 7.0) that the FTP is so slow.
Details: RedHat 7, kernel 2.2.17, on 486/66 box (with Pentium Overdrive
chip), 32 megs RAM.
CPU usage on the linux box stays consistently low, and does not exceed 50%
total usage, even when FTP is in progress.
I have tried the following:
- removed all ip_masq_* Modules using rmmod
- Only bring up eth1, which is the local internal LAN (on subnet
- Bring up both ETH0 and ETH1, but don't enable IP Masquerading
- Tried starting up SAMBA, it runs so slowly as to be unusable as well, and
Windows has timeouts trying to access SAMBA.
- Tried accesing the FTP server via its local ethernet IP (10.42.42.2) and
its Internet IP (24.xx.yy.zz) and got the same slow rate of transfer and
"apparent LAN freezeup".
I am completely stumped. I have set up other FTP Servers before and they've
always performed well on the local LAN. What's going on? How can I diagnose
this? It's not just SLOW it freezes up.