How often should we expect 400 Bad Request

400apache-2.2bad-requesthttp

We run an Apache2 web server which has somewhere in the vicinity of 2-3 million pages served every day (only HTML+CSS+Javascript, images and other content is served with Lighttpd). Our daily logwatch e-mail outputs somewhere between 3-5 "400 Bad Request" items a day. It is mostly for the same URLs every day, but rarely more than 1 time per URL. The URLs listed are mostly for standard page views on our website (URLs that almost every user will visit).

When grepping the error.log for the IPs listed in the access.log as having received the error, the result is always [error] [client xxx.xxx.xxx.xxx] request failed: error reading the headers, referer: xxx.

My assumption is that these are nothing to worry about, at least when they are this infrequent.

Is the number of errors we are seeing here produced by dropped connections, or something similar? What should I examine to figure it out? Should I just leave it alone?

Best Answer

Based on what you are seeing, if the same IPs logging the errors can later successfully access the site, then it is probably very safe to ignore the infrequent errors for the rational that you have presented.

Related Solutions

Redirecting requests that would result in an HTTP 400 (Bad Request) error (Apache 2.2)

You could define a custom ErrorDocument for the 400 Errors like so:

ErrorDocument 400 /cgi-bin/handle400.cgi

and then have that cgi (or php or servlet or whatever) do the header rewriting and location redirecting.

EDIT: because of Jacek's answer I just tested above solution to confirm it works on Apache 2.2.

My Server Config:

ScriptAlias     /cgi-bin/ "/var/www/cgi-bin/"
ErrorDocument   400 /cgi-bin/handle400.pl

lukas$ cat /var/www/cgi-bin/handle400.pl

#!/usr/bin/perl
print "Content-type: text/html\n\n";
while (my ($key, $val) = each %ENV) {
        print "$key = $val<BR>\n";
}
exit 0;

Now when accessing the broken URL that would produce an error 400 Bad Request before, I now get the following (partial) output:

...
REDIRECT_REQUEST_METHOD = GET
REDIRECT_STATUS = 400
REMOTE_ADDR = xx.xx.xx.xx
REQUEST_URI = /%&%28%7B$%7Beval%28base64_decode%28$_SERVER%5BHTTP_EXECCODE%5D%29%29%7D%7D%7C.+%29&%/
GATEWAY_INTERFACE = CGI/1.1
SCRIPT_URL = /cgi-bin/handle400.pl
...

So you do get enough information to do a proper status code change and location redirect.

Uploading file > 1 MB on Django admin gives 400 Bad Request response

I am going to answer this myself as the problem has been resolved. Thanks very much to both Redmumba and Graham Dumpleton for their comments.

The problem was certainly not with Django (as we had already established). However, it turned out not to be with Apache. The problem was with the firewall on the system that the system admins had forgotten about completely (sigh). Apparently, the firewall had a file size limit of 1MB imposed.

Best Answer

Related Solutions

Redirecting requests that would result in an HTTP 400 (Bad Request) error (Apache 2.2)

Uploading file > 1 MB on Django admin gives 400 Bad Request response

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