Hi,
I've just become involved with a system running apache2.0.55 on ubuntu
with linux 2.6.17.
The system is currently unable to run due to repeated downloads of a
large number of pdfs by systems located in China. These are hogging all
sockets and eventually causing apache to die (I'm appending more details
below in case I've got the wrong end of the stick). The ip address of
these systems varies; they are not a single block, although they are
obviously working together (different ip addresses will ask for
sequentially related pdfs). Each ip address will request multiple files
in parallel.
I'm told that the limit_ipconn module would solve my problem by limiting
the simultaneous accesses from any one ip address. There is no version
of this available for apache2 on ubuntu. I'm wondering if this is
because similar abilities have been built into apache2 itself, but
haven't managed to find any.
Does anyone have any suggestions?
Thanks
Graham
-----------------------------------------------
Notes from log:
The system is running ok, not at particularly heavy load (<1.0), and
apache is apparently running ok and not reporting errors [corrected later].
Tailing the apache log file shows that the only accesses to the system
are GETs of pdfs from two chinese systems, 218.4.152.91 and
222.218.254.221, which are obviously running the same software.
These systems are trying to systematically work their way through
downloading all chinese pdfs. When a pdf is too large and the download
times out, they immediately try again (at any one moment each system is
trying to download 3 or 4 pdfs).
If I restart apache, I immediately get accesses from all over the place,
including the 2 chinese systems. Eventually the Chinese accesses capture
all the apache processes, and nothing else can get access.
'Solution' found for this: turn apache off for a few minutes. The
chinese systems went away, and all was fine again.
One hour later ΒΆ
The chinese systems, and the problems, returned. A little more data this
time.
Once the chinese systems are established, netstat shows that they occupy
most sockets but are mostly in CLOSE_WAIT state. All other requests are
stuck in SYNC_RECV.
After this continues for a while the apache processes gradually start to
die off with the following sequence:
alert] (11): setuid: unable to change to uid: 33 (33 is www-data)
[alert] Child 691 returned a Fatal error... Apache is exiting!
[emerg] (43): couldn't grab the accept mutex
semop: Invalid argument
---------------------------------------------------------------------
The official User-To-User support forum of the Apache HTTP Server Project.
See <URL:http://httpd.apache.org/userslist.html> for more info.
To unsubscribe, e-mail: [EMAIL PROTECTED]
" from the digest: [EMAIL PROTECTED]
For additional commands, e-mail: [EMAIL PROTECTED]
