Barrett Consulting Group Sendmail Page

dont use, too old

What you currently can find here:

A "milter" based filter for sendmail 8.12.X which gets rid of nearly all the bad attachements (exe,bat,com,js,...,vbs,...) and reanmes them to *@XXX, and optionally gets rid of the HMTL based part of email of SCRIPT based stuff only, rejects certain mail which have attachements.

it is currently in beta stage, please be aware of this.
I have started looking into developping it with one other person whose filter has some features my filter does not have and vice versa.

Currently writing:

use it in combination with a virus scanner
Probably make the support in a way that it will be able to use a variety.

Done (latest)

re-entrant code
checking attachements over a large range of blocks.
bug fixes (see code)

Milter based Sendmail (8.12.X) filter.

What it does

find HTML tags and wipes anything between (option -h)
find SCRIPT tags and wipes anything between
find OBJECT tags and wipes anything between
find attachments, checks the name and if it matches certain extension, replaces them
sends messages to the syslog (everytime)
finds particular attachemnents and rejects the mail (sends mail to both, receiver and postmaster)
saves the "bad" message to /etc/mail/FilteredMessages (with recv,sender and message num)

Requirements

sendmail version greater (or equal to) 8.12.X
sendmailfilter.c
gcc
directory /etc/mail/FilteredMessageFiles must exist and root writeable

OS tested on

Linux, it has been running without crashing for 11 days now and we get plenty of mail from different places, machines, mailers, os's etc.
I'd love to hear from other people who used it!!!
Find the bugs, please!

Read

libmilter/README it explains what to do
some of the source code of sendmailfilter.c (sorry manual isnt available yet)

Setup for the sendmail mc file

Include the two follwing lines into you sendmail.mc file and compile it using the m4 macro processor. (see cf/README)

define(`_FFR_MILTER', `1')dnl
INPUT_MAIL_FILTER(`filter1',`S=unix:/var/run/f1.sock')

Note: it does not matter how you name the filter, this is only used for sendmails config file. However the name of the soccket you specify here must be the same you specify when you start sendmailfilter!

How to compile it

Copy the filter into a directory called "/usr/local/src/sendmailfilters"
Edit the file and replace the "your.domain.com" with your domain name. (this is required for internal mail check and postmaster address)
Edit the file and comment out some of the debug messages "dfprintf(...)" or else it will fill up your logs, there is a fair amount of them in it.
It fills up my maillogs very regular!
You might want to keep them first to see the filter in "action". It logs the normal stuff to the system logs and the debug messages to /usr/local/src/sendmailfilters/sendmailfilter.log!
Make yourself a Makefile and put into it:
SENDMAILDIR=sendmail-8.12.1
CFLAGS=-I../$(SENDMAILDIR)/sendmail -I../$(SENDMAILDIR)/include
LDFLAGS=-L../$(SENDMAILDIR)/obj*/libmilter -L../$(SENDMAILDIR)/obj*/libsmutil
LIBS=../$(SENDMAILDIR)/obj*/libmilter/libmilter.a ../$(SENDMAILDIR)/obj*/libsmutil/libsmutil.a
all: sendmailfilter codetest
sendmailfilter: sendmailfilter.o
gcc -o $@ $? $(CFLAGS) $(LIBS) -lresolv -lnsl -lpthread
compile it using
make

How to run the filter

Remove the old socket and then run the program:

rm /var/run/f1.sock
sendmailfilter -h -p unix:/var/run/f1.sock

where the options are:

-h: OPTIONAL turn on html wipe (if somebody sends html only you will not see anything but you do not get those stupid advertisings either.....)
-i: OPTIONAL check internal based mail too
-p socket: REQUIRED connects to the specified socket.

If this returns straight away, something is wrong.
Increase debugging level to see whats wrong.

How tested

A friend (sadly he died in a Kajak Accident) of mine constantly sent me different files from different mailers from different OS's. He made me aware of a few bugs, he used the program as well.
I have send to the filter the following files in various orders and combinations (till it survived) with vcard/without vcard attachment, using HTML/SCRIPTS, html only etc:
explorer.exe, addusers.vbs, gina.c, gina.g, ginasetup.exe, resume.doc(yes the one), no attachments, various dll, some word docs, atmcntrl.exe, netscape.exe (yes that big one), mpg's, tgz, tar etc etc.
Currently its stable.

Bugs

no configuration file, changes must be made to the program by hand (careful, dont break the glass of the screen!).

Contact

Jobst Schmalenbach

Download Area(Warranty Notice):

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