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("[email protected]", "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
28 comment
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
Jeremie,
Add sendmail user to your /webroot/etc/passwd file
Incase anyone else is having the same problem…. try femail instead… much easier 🙂
Ah, thanks here is url for femail
http://quigon.bsws.de/femail/
Or just change ‘username = getlogin();’ to ‘username = “www-data”;’ in mini_sendmail.c 🙂
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-dataâ€; 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
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”;
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?
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-dataâ€;
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?
We have multiple chrooted apaches running with different user rights, so username = “www-dataâ€; 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
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
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
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.
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
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.
You should have a valid domain, that if they reverse lookup it will still resolve.
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>
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…
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.
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= "[email protected]";
$headers = "From: $from_email";
$body = "Hi, n This is a test mail from $from_name .”;
$subject = “Test mail from besa”;
$to = “[email protected]”;
if (mail($to, $subject, $body, $headers))
{echo “mail send success!”;}
else {echo “mail fail…”;}
?>
[/code]
sendmail.ini
logfile “aptanaxampp-win32-1.7.3xamppsendmailsendmail.log”
smtp_server=wnameserver.puk.ac.za
smtp_port=1117
default_domain=nna.ac.za
error_logfile=error.log
[email protected]
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 [email protected]
; For Unix only. You may supply arguments as well (default: “sendmail -t -i”).
; http://php.net/sendmail-path
sendmail_path = “C:aptanaxampp-win32-1.7.3xamppsendmailsendmail.exe -tâ€
; 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 = “aptanaxampp-win32-1.7.3xamppapachelogsphp_mail.log”
I receive the message mail send success! but no mail is delivered.
Hope you can help.
can i know how to configure for windows 7? to send mail using php
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 [email protected]
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.
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
GOOGLE IS YOUR FRIEND!
https://www.google.com/search?q=what+is+chroot&aq=f&sugexp=chrome,mod=1&sourceid=chrome&ie=UTF-8
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 [email protected] -sxxx.xxx.xxx.xxx -v [email protected].
The email.dat looks like:
to:[email protected]
from:[email protected]
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 = [email protected]
——_=_NextPart_7693.NPBM–
Can anyone help me out why I am getting this error.
Amrita
I’ve done all the above but mail() still returns false… I have nothing in the logs, how can I debug that? I’m getting crazy
Solved! I had to create /dev/zero, /dev/urandom and /dev/null