Setup sendmail php mail() support for chrooted Lighttpd or Apache web server

by on November 8, 2006 · 26 comments· LAST UPDATED November 8, 2006

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Once chroot() call is applied to chrooted lighttpd or apache web server, you lost the connection with real /usr/sbin/sendmail program.

The php mail() function allows you to send mail. For the Mail functions to be available, PHP must have access to the sendmail binary on your system during compile time. If you use another mail program, such as qmail or postfix, be sure to use the appropriate sendmail wrappers that come with them. PHP will first look for sendmail in your PATH, and then in the following: /usr/bin:/usr/sbin:/usr/etc:/etc:/usr/ucblib:/usr/lib. It's highly recommended to have sendmail available from your PATH. Also, the user that compiled PHP must have permission to access the sendmail binary. Because of chroot you cannot access anything outside jail.

Even if you copy /usr/sbin/sendmail it will not work because it needs all other directories in /var and sendmail config file in /etc/mail directory.

So how do I configure php mail() support in chrooted jail webserver?

  • Don't use php mail() use php SMTP class to send email (recommended method #1)
  • Install complete sendmail in chrooted jail (this is too much work)
  • Install statically linked mini_sendmail and /bin/sh in chrooted jail. (recommended method #2)

Task: Setting up static mini_sendmail for chrooted apache or lighttpd web server

mini_sendmail reads its standard input up to an end-of-file and sends a copy of the message found there to all of the addresses listed. The message is sent by connecting to a local SMTP server. This means mini_sendmail can be used to send email from inside a chroot(2) area. However, it needs to create a pipe so you need to copy shell to chroot as well.

Install mini_sendmail

Type the following commands:
# cd /opt
# wget http://www.acme.com/software/mini_sendmail/mini_sendmail-1.3.6.tar.gz
# tar -zxvf mini_sendmail-1.3.6.tar.gz
# cd mini_sendmail-1.3.6

Compile mini_sendmail

# make

Copy mini_sendmail to chrooted directory

Assuming that your chrooted directory is /webroot
# mkdir -p /webroot/usr/sbin
# cp mini_sendmail /webroot/usr/sbin/sendmail

Configure php for mini_sendmail (sendmail)

Goto /webroot directory
# vi etc/php.ini
OR
# vi /webroot/etc/php.ini

Setup sendmail path

sendmail_path = /usr/sbin/sendmail -t -i

Restart Apache webserver

# /etc/init.d/httpd restart
# apachectl restart

Or Restart lighttpd web server

# /etc/init.d/lighttpd restart

Copy /bin/sh or /bin/bash

# cp /bin/sh /webroot/bin
# l2chroot /bin/sh

Test your setup

Create php script - mailtest.php as follows:
<?php
mail("you@yourcorp.com", "PHP Test mail", "Hope this works! ");
?>

Point browser to http://yourcrop.com/mailtest.php

More troubleshooting tips

(a) Make sure you have /etc/resolv.conf and /etc/hosts files available in chrooted jail at /webroot/etc directory.

(b) Make sure your mail server accept connection from localhost (default)

(c) Consult /var/log/maillog (or your MTA log file) outside jail for more information
# tail -f /var/logm/maillog

Continue reading the rest of Lighttpd security series articles

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{ 26 comments… read them below or add one }

1 jeremie January 30, 2007 at 10:54 pm

Hello,

I’ve followed your article in order to setup mini_sendmail on my chroot Apache2 webserver.

Everythings is ok except this error in the apache’s error.log :

/usr/sbin/sendmail: can’t determine username

I’m stuck on this problem, and help would be appreciated !

Best regards,

Jeremie Werner

Reply

2 nixCraft February 1, 2007 at 10:06 pm

Jeremie,

Add sendmail user to your /webroot/etc/passwd file

Reply

3 boohoo @ mini_sendmail April 28, 2007 at 5:18 pm

Incase anyone else is having the same problem…. try femail instead… much easier :)

Reply

4 nixCraft April 29, 2007 at 3:35 am

Ah, thanks here is url for femail

http://quigon.bsws.de/femail/

Reply

5 Fabian June 24, 2007 at 2:56 pm

Or just change ‘username = getlogin();’ to ‘username = “www-data”;’ in mini_sendmail.c :)

Reply

6 tomcat August 22, 2007 at 10:12 pm

Hi i have also an problem :(
If i execute the testmail php file als root
./php /webroot/home/lighttpd/tmail.php
it works fine but if i test it using lighttpd it doesnt work.
I got no errormessages in log but i think its this problem: /usr/sbin/sendmail: can’t determine username.
I try to add sendmail user to /webroot/etc/passwd file, sendmail:x:65002:108::/home/sendmail:/sbin/nologin
but it dont work
When i change ‘username = getlogin();’ to ‘username = “www-data”; in mini_sendmail.c i got compile error :(
When i write username = ‘www-data’ i can compile but it dosnt work over my Webserver only als root ./php /webroot/home/lighttpd/tmail.php :((
I also try femail but there i get this error:
cc femail.o openbsd_compat.o -o femail
femail.o(.text+0x570): In function `build_from':
: undefined reference to `strlcpy’
femail.o(.text+0x61b): In function `build_from':
: undefined reference to `strlcpy’
femail.o(.text+0x665): In function `parse_message':
: undefined reference to `fgetln’
femail.o(.text+0x12e7): In function `read_reply':
: undefined reference to `strlcpy’
femail.o(.text+0x17ac): In function `parse_config':
: undefined reference to `fgetln’
femail.o(.text+0x1953): In function `parse_config':
: undefined reference to `strlcpy’
femail.o(.text+0x1b03): In function `next_token':
: undefined reference to `strlcpy’
collect2: ld returned 1 exit status
make: *** [femail] Error 1

Please help me

Reply

7 evilghost September 4, 2007 at 1:14 pm

Users having issues with the “can’t determine username” error message can modify the source code and re-run make. I’ve been able to successfully do this without playing with /etc/passwd by manually specifying the user and bypassing the getlogin() function.

/* username = getlogin(); */
username = “www-data”;

Reply

8 yudai November 9, 2007 at 12:56 pm

Whenever I try the test php, I get the following error in ssh:
/bin/sendmail: unexpected response 550 to RCPT TO command
What am I doing wrong here?

Reply

9 gnif November 18, 2007 at 4:27 am

A few things that arn’t clear here. If you are running inside a chroot, and using suEXEC or suPHP, you must make sure that /bin/sh, and sendmail are executable bu the user.

If you are using virtual users, you must make the modification to mini_senmail by evilghost

/* username = getlogin(); */
username = “www-data”;

Reply

10 Nick November 30, 2007 at 11:33 am

Is it possible to add mail() support to an existing php install that wasn’t compiled with access to sendmail without re-compiling? For example adding a module?

Reply

11 pero June 10, 2008 at 11:30 am

We have multiple chrooted apaches running with different user rights, so username = “www-data”; is not a solution for the problem!

In this case you have to copy the libc6 libraries into to jail!

After that getlogin() will work, if you have the apache user in /chrootdir/etc/passwd

Reply

12 Robyn July 16, 2008 at 2:23 pm

Can somebody please tell me. mail() function now works properly, but when testing with PHPMailer, it fails.

PHPMailer has support to add recipients with the AddAddress($email, $name) function. If I don’t fill the $name variable, mail will be sent normally, but if I fill it, I get this error:

/usr/sbin/sendmail: unexpected response 501 to RCPT TO command

Thanks in advance

Reply

13 Robyn July 22, 2008 at 8:15 am

For my previous post: there’s a fix for mini_sendmail’s recipient handling bug. Patch mini_sendmail.c with the code on this link:

https://dev.openwrt.org/cgi-bin/trac.fcgi/browser/packages/net/mini_sendmail/patches/200-fullname.patch?rev=8530

Bye

Reply

14 Jonathan April 6, 2009 at 3:57 am

I had the same problem as tomcat when compiling femail on Debian.

I have patched the femail.c file to include the missing functions it was referencing. You can download the fixed femail for debian based linux < there.

Reply

15 alex June 22, 2009 at 7:19 pm

This step is wrong.

# cp /bin/sh /webroot/bin
# l2chroot /bin/sh

it should be (I think)

#mkdir -p /webroot/bin/
#cp /bin/sh /webroot/bin/
#l2chroot /bin/sh

Reply

16 John Ian R. Medilo August 15, 2009 at 9:35 pm

i can already send email thru send mail to gmail account.. the problem is that i cannot received to my company email… when i use the settings

# “Smart” relay host (may be null)
DSmyhost.host.com

gmail account cannot received.

Reply

17 John Ian R. Medilo August 17, 2012 at 10:01 am

You should have a valid domain, that if they reverse lookup it will still resolve.

Reply

18 Chris September 7, 2009 at 9:39 pm

Jonathan –

There’s no need to rebuild it – the necessary functions are included in the original femail distro. Just open the Makefile and comment out this line:

CFLAGS+= -DHAS_FGETLN -DHAS_STRLCPY

And then run a ‘make’. The author included versions of the functions from OBSD>

Reply

19 Chris September 7, 2009 at 9:40 pm

Also, I find it a bit… beyond silly… that people go through the trouble of setting up a chroot for Apache and then have no problem copying a shell into that chroot. That’s a great way to provide a potential attacker with a much bigger attack surface…. Mini_sendmail is way overkill…

Reply

20 Will May 6, 2010 at 2:46 am

To compile femail on debian I had to install the freebsd-buildutils package & the above makefile edit

I also compiled and copied to /webroot/usr/bin/sendmail and testing with

chroot /webroot/ sendmail -v ***@gmail.com < email.txt

it works fine

testing from php only works with /webroot/bin/sh is bash

Chris this is an old subject but any input? I want to remove sh as per your comment.

Reply

21 Tinus September 2, 2010 at 6:29 am

Hi

I am having problems with sendmail.
I am running appache on windows.

My php looks as follow:
[code]
<?php
$from_name = "BESAWEB";
$from_email= "123690@swu.ac.za";
$headers = "From: $from_email";
$body = "Hi, \n This is a test mail from $from_name .";
$subject = "Test mail from besa";
$to = "123690@swu.ac.za";
if (mail($to, $subject, $body, $headers))
{echo "mail send success!";}
else {echo "mail fail…";}
?>
[/code]

sendmail.ini

logfile “\aptana\xampp-win32-1.7.3\xampp\sendmail\sendmail.log”

smtp_server=wnameserver.puk.ac.za
smtp_port=1117
default_domain=nna.ac.za
error_logfile=error.log
auth_username=12332690@nwu.ac.za
auth_password=Janse

In php.ini
[mail function]
; For Win32 only.
; http://php.net/smtp

SMTP = wnameserver.puk.ac.za

; http://php.net/smtp-port

smtp_port=1117

; For Win32 only.
; http://php.net/sendmail-from

sendmail_from =123690@nwu.ac.za

; For Unix only. You may supply arguments as well (default: “sendmail -t -i”).
; http://php.net/sendmail-path

sendmail_path = “C:\aptana\xampp-win32-1.7.3\xampp\sendmail\sendmail.exe -t”

; Force the addition of the specified parameters to be passed as extra parameters
; to the sendmail binary. These parameters will always replace the value of
; the 5th parameter to mail(), even in safe mode.
;mail.force_extra_parameters =

; Add X-PHP-Originating-Script: that will include uid of the script followed by the filename
mail.add_x_header = Off

; Log all mail() calls including the full path of the script, line #, to address and headers
mail.log = “\aptana\xampp-win32-1.7.3\xampp\apache\logs\php_mail.log”

I receive the message mail send success! but no mail is delivered.

Hope you can help.

Reply

22 prasanth January 14, 2011 at 4:35 pm

can i know how to configure for windows 7? to send mail using php

Reply

23 lelutin March 4, 2011 at 11:19 pm

Nice that trick about hardcoding the user string!

I’ve just lost 3h debugging this. Since there’s nothing in the apache log it was pretty painful to debug.

Here’s a trick to debug what’s happening inside the chroot on the command line:

echo ‘Subject: test’ | chroot /webroot /usr/sbin/mini_sendmail -v you@yourdomain.com

Also, the article mentions copying /bin/sh to the chroot, but if /bin/sh is not statically linked, you’ll have a non working setup. You need to ldd /bin/sh and copy all the libraries it uses inside the chroot.

Reply

24 niaki May 3, 2012 at 7:19 am

hi;
i want to knew about chroot what is that exactly and how can i use it?
please help me about this im beginner in linux
thanks

Reply

25 will August 17, 2012 at 2:13 pm
26 Amrita April 15, 2013 at 6:02 am

Hi,

I am trying to use mini_sendmail utility to send mails.
But I get Unexpected EOF error when i execute the following command,

cat email.dat | /usr/local/sbin/mini_sendmail -t -p25 -fabs@xyz.com -sxxx.xxx.xxx.xxx -v abs@zzz.xyz.com.

The email.dat looks like:

to:abs@xyz.com
from:abs@zzz.xyz.com
date:Wed, 30 Jan 2013 23:59:00 +0000
subject: Email
MIME-version: 1.0
Content-type: multipart/mixed; boundary=”—-_=_NextPart_7693.NPBM”

This message is in MIME format.

——_=_NextPart_7693.NPBM
Content-Type: text/plain

Event Time: Wed, 30 Jan 2013 23:59:00.377 +0000^M
Nodename = Amrita@1

——_=_NextPart_7693.NPBM–

Can anyone help me out why I am getting this error.

Amrita

Reply

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