MailGatewayDeploymentGuide-V1.8

Proxmox Mail Gateway

Deployment Guide

5/21/2010

MailGatewayDeploymentGuide-V1.8.docx

Proxmox Server Solutions GmbH

Kohlgasse 51/10 A-1050 Vienna [email protected] www.proxmox.com

© 21.05.2010 Proxmox Server Solutions GmbH 2 49

Proxmox Server Solutions GmbH reserves the right to make changes to this document and to the products described herein without notice. Before installing and using the

software, please review the latest version of this document, which is available from http://www.proxmox.com. NOTE: A license to the Proxmox Software usually includes the right to product updates for one (1) year from the date of purchase. Maintenance can be renewed on an annual basis. All other product or company names different from Proxmox may be trademarks or registered trademarks of their owners. Copyright © 2010 Proxmox Server Solutions GmbH. All rights reserved. No part of this publication may be reproduced, photocopied, stored in a retrieval system, or transmitted without the express prior written consent of Proxmox.

http://www.proxmox.com/




Table of Contents

1 Introduction .................................................................................................... 5 2 Proxmox Mail Gateway Integration ..................................................................... 6

2.1 E-mail system without Proxmox ................................................................... 6 2.2 E-mail system with Proxmox ........................................................................ 6 2.3 Proxmox in the Intranet .............................................................................. 8

2.3.1 Default port settings ............................................................................ 8 2.3.2 Alternative port settings (e.g. for MS Exchange) ..................................... 8

2.4 Proxmox in DMZ (demilitarized zone) ...........................................................10 2.5 Proxmox with multiple e-mail server and mail domains ..................................11

3 Performance Tuning ........................................................................................12 3.1 Hardware benchmarks ...............................................................................12 3.2 Backup MX ...............................................................................................12 3.3 Local DNS cache ........................................................................................12 3.4 Blocking Emails on SMTP level ....................................................................13

3.4.1 Greylisting .........................................................................................13 3.4.2 Sender Policy Framework – SPF ...........................................................14 3.4.3 Real time Blacklists (RBL)....................................................................14 3.4.4 Local DNS RBL cache – Spamhaus Datafeed Service ...............................15

3.4.4.1 Configuring local DNS blacklist caches ............................................15 3.4.5 Receiver Verification ...........................................................................16

3.4.5.1 Proxmox Solutions .......................................................................16 3.4.5.2 Enabling Verify Receivers ..............................................................17

3.4.5.2.1 Settings for Exchange 2003 SP2 ..................................................18 3.4.5.2.2 Settings for Exchange 2007 SP1 ..................................................21

4 Rule System ...................................................................................................22 4.1 Default Rules ............................................................................................24

4.1.1 Block Viruses .....................................................................................24 4.1.2 Virus Alert .........................................................................................24 4.1.3 Block Dangerous Files .........................................................................25 4.1.4 Mark Spam ........................................................................................25

4.2 Custom Rules ............................................................................................26 4.2.1 Enable Spam and Virus quarantine .......................................................26 4.2.2 Enable Spam quarantine for just a selection of users ..............................26 4.2.3 Enable Spam quarantine for existing LDAP users ....................................27 4.2.4 Block Spam e-mails with a score higher 10 ............................................29 4.2.5 BCC object – An simple archive solution ................................................33 4.2.6 Block Video and Audio Attachments ......................................................33 4.2.7 Add Admin Notification to Rules ...........................................................34 4.2.8 Preventing directory harvesting attacks with LDAP object ........................34 4.2.9 Block Video and Audio Attachments for LDAP Groups ..............................35

5 Proxmox HA Cluster – High availability ..............................................................37 5.1 Load Balancing with MX Records..................................................................38 5.2 Multiple Address Records ............................................................................39 5.3 Using third party Firewall features ...............................................................39

6 Hardware selection and Virtualization ................................................................40 6.1 Physical Hardware .....................................................................................40

6.1.1 Certified Hardware .............................................................................40 6.2 Proxmox VE (http://pve.proxmox.com) ........................................................40 6.3 VMware™ .................................................................................................40

6.3.1 Settings for VMware™ ESX, ESXi and vSphere .......................................41 6.3.1.1 Settings for the Proxmox Mail Gateway Virtual Machine ....................41

6.3.1.1.1 RAM settings .............................................................................41 6.3.1.1.2 VMware Tools............................................................................41 6.3.1.1.3 Enable VMI Paravirtualization ......................................................41 6.3.1.1.4 Enable time synchronization .......................................................42




6.3.2 Settings for a VMware™ Server 2 .........................................................42 6.3.2.1 Host memory settings ...................................................................42 6.3.2.2 Settings for Proxmox Mail Gateway Virtual Machine ..........................43

6.3.2.2.1 RAM settings .............................................................................43 6.3.2.2.2 VMware Tools............................................................................43 6.3.2.2.3 Enable VMI Paravirtualization ......................................................43 6.3.2.2.4 Enable time synchronization .......................................................44

6.4 OpenVZ ....................................................................................................45 7 Troubleshooting and technical support ...............................................................47 8 Table of figures ...............................................................................................48 9 Appendix .......................................................................................................49




1 Introduction The huge amount of e-mail traffic is a challenge for every e-mail environment. The daily

e-mail routine brings along some major problems, this includes: performance, reliability, regulation under public law and e-mail threads like viruses or Phishing attacks. E-mail is an essential service for any organization, and professionally managed e-mail improves organizational workflow and customer satisfaction. A missed e-mail could mean a lost opportunity, or it could cause a public-relations problem that no organization would want. How does Proxmox work? When an e-mail arrives at the Proxmox Mail Gateway, it is analyzed and forwarded to your e-mail server which is responsible for sending the e-mail to the receiver. If the e-mail server is not working, Proxmox Mail Gateway temporarily stores the message in the e-mail queue for later transfer. The process works similar for outgoing e-mails.

This document covers samples and deployment information how to integrate and customize Proxmox in your e-mail environment.

Note: See also the Proxmox Mail Gateway Administration Guide for a detailed product description.




2 Proxmox Mail Gateway Integration

2.1 E-mail system without Proxmox In a sample configuration, your e-mail traffic (SMTP) arrives on the firewall and will be forwarded directly to your e-mail server.

Figure 2-1 System without Proxmox Mail Gateway

2.2 E-mail system with Proxmox A single Proxmox Mail Gateway Server can handle unlimited mail domains with multiple internal mail servers and millions of e-mails per day. For high availability and maximum performance it is recommended to use a Proxmox HA Cluster, see chapter 5 Proxmox HA Cluster – High availability. Proxmox Mail Gateway can process incoming AND outgoing SMTP traffic by using different ports. One port is assigned to incoming, one port for outgoing e-mails. With the integrated Proxmox system all your e-mail traffic is forwarded to the Proxmox Mail Gateway which filters the whole e-mail traffic and removes unwanted e-mails. You

can manage incoming and outgoing e-mail traffic.

Figure 2-2 Incoming e-mail with Proxmox Mail Gateway




Many mail filter solutions do not scan outgoing mails. Opposed to that Proxmox Mail Gateway is designed to scan both incoming and outgoing mails. This has two major advantages:

Figure 2-3 Outgoing with Proxmox Mail Gateway

1. Proxmox is able to detect viruses sent from an internal host. I many countries you are liable for not sending viruses to other people. Proxmox outgoing e-mail scanning feature is an additional protection to avoid that.

2. Proxmox can gather statistics about outgoing e-mails too. Statistics about incoming e-mails looks nice, but they are quite useless. Consider two users, user-1 receives 10 mails from news portals and wrote 1 mail to a person you never heard from. While user-2 receiver 5 mails from a customer and sent 5 mails back. Which user do you consider more active? I am sure its user-2, because he communicates with your customers. Proxmox advanced address statistics can show you this important information. Solution which does not scan outgoing mail can’t do that.




2.3 Proxmox in the Intranet

2.3.1 Default port settings

The default configuration of the Proxmox Mail Gateway uses port 25 for incoming and port 26 for outgoing e-mails.

Figure 2-4 Incoming default port settings (port 25) Outgoing Mails: Configure your mail server to send all e-mails to the Proxmox Mail Gateway, port 26.

Note: Proxmox receives the outgoing e-mails on port 26, so Proxmox knows its internal trusted e-mail. After processing, Proxmox sends the e-mails to Internet, using standard port 25.

Figure 2-5 Outgoing default port settings (port 26)

2.3.2 Alternative port settings (e.g. for MS Exchange)

Sometimes it is not possible to change the outgoing port due to third party software limitations or existing network configurations (e.g. changing MS Exchange to another sending port will have impact on Exchange internals and it’s not recommend) To receive e-mails you have to do port forwarding at your Firewall. So that you’re external IP and port 25 shows to the Proxmox Mail Gateway IP and port 26.




Figure 2-6 Incoming alternative port settings (port 26) With MS Exchange you should not use port 26 for outgoing so you have to switch these two values (25 and 26). In the end you have to use port 25 for outgoing and port 26 for incoming mails.

Figure 2-7 Outgoing alternative port settings (port 25)




2.4 Proxmox in DMZ (demilitarized zone) To run a DMZ Zone you have to adjust your Firewall settings. The intranet (Local) and DMZ needs to have different IP Networks, for example:

Interface Zone IP Address Net mask

eth0 Local 192.168.1.1 255.255.255.0

eth1 Internet 10.0.0.2 255.255.255.0

eth2 DMZ 192.168.16.1 255.255.255.0

Figure 2-8 Proxmox in DMZ




2.5 Proxmox with multiple e-mail server and mail domains You can use Proxmox Mail Gateway sending e-mails to different internal e-mail servers. For example you can send e-mails addressed to domain.com to your first e-mail server, and e-mails addressed to subdomain.domain.com to a second one. In the e-mail proxy transport section add the IP addresses or hostname, SMTP ports and mail domains of your additional e-mail servers.

Figure 2-9 Multiple e-mail servers

Note: you need for each domain an appropriate license, otherwise it will not work!




3 Performance Tuning

3.1 Hardware benchmarks Please use the command line tool “proxperf” to get an overview about your hardware and DNS performance.

Note: Never run “proxperf” if the system is under load.

Here is a sample output of “proxperf”: proxmox:~# proxperf CPU BOGOMIPS: 8489.64 REGEX/SECOND: 410814 HD SIZE: 6.89 GB (/dev/sda2) BUFFERED READS: 116.38 MB/sec

AVERAGE SEEK TIME: 8.09 ms FSYNCS/SECOND: 1084.51 DNS EXT: 46.26 ms DNS INT: 1.05 ms (domain.com) DNSBL: 35.47 ms (zen.spamhaus.org) proxmox:~# Please compare your results against this reference. If you get lower results please

analyze your hardware and DNS setup – for comments email your results to [email protected].

3.2 Backup MX Using your ISPs mail server is not a good idea, because many ISPs do not use advanced spam prevention techniques. And spammers know this and they use your ISP backup MX

to work around your Proxmox spam filtering. Additionally, you can never benefit of blocking spam messages on SMTP level. If you need redundancy, it is recommended to run a second Proxmox server in HA Cluster mode to avoid lower spam detection rates

3.3 Local DNS cache Proxmox includes a local DNS cache. It is recommended to enable it if you do not have access to fast (internal) DNS servers, or if you want to reduce the load on those servers.

Figure 3-1 Use local DNS Cache

mailto:[email protected]




3.4 Blocking Emails on SMTP level Blocking emails before they reach your network saves your internet bandwidth and reduces processing power. By doing the following, you can reduce your email traffic by more than 90 %, depends on your environment.

If you want to exclude some senders or receivers from getting blocked on the SMTP level, just enter in the Mail proxy whitelist.

Figure 3-2 Mail proxy whitelist

3.4.1 Greylisting

Typically, a server that utilizes Greylisting will record the following three pieces of information (referred to as triplet) for all incoming e-mail.

The IP address of the connecting host The envelope sender address The envelope recipient address

The client is checked against the mail server's internal whitelists (if any) first. Then, if the triplet has never been seen before, it is greylisted for a period of time (how much

time is dependent on the server configuration). The e-mail is rejected with a temporary error. The assumption is that since temporary failures are built into the RFC specifications for e-mail delivery, a legitimate server will attempt to connect again later

on to deliver the e-mail.

Greylisting is effective because many mass e-mail tools utilized by spammers are not set up to handle temporary failures (or any failures for that matter) so the Spam is never

received.

This feature can reduce e-mail traffic up to 50%. Greylisted e-mails never reach your mail server and your mail server will stop sending useless "Non Delivery Reports" to spammers, filling up the queue.

If a sender has a valid SPF record, he will never be greylisted.




3.4.2 Sender Policy Framework – SPF

Domains use public records (DNS) to direct requests for different services (web, e-mail, etc.) to the machines that perform those services. All domains already publish e-mail (MX) records to tell the world what machines receive e-mail for the domain. SPF works by domains publishing "reverse MX" records to tell the world what machines send e-mail for the domain. When receiving a message from a domain, the recipient can check those records to make sure e-mail is coming from where it should be coming from. Please make sure, that you deploy a valid SPF record for your mail domain.

Note: see http://www.openspf.org for setting up a SPF for your mail domain.

3.4.3 Real time Blacklists (RBL)

Proxmox can use RBL checks on SMTP level to reject e-mails. Therefore Proxmox has to query the RBL server for every SMTP connection. Proxmox use the following RBL providers by default:

• Spamhaus.org • dsbl.org

Figure 3-3 Enable RBL checks

http://www.openspf.org/




3.4.4 Local DNS RBL cache – Spamhaus Datafeed Service

Each e-mail leads to a DNS query to the RBL server of spamhaus and dsbl. If these servers are under heavy it cannot be guaranteed that you will get an answer – also if you

are running a high traffic site it is recommended to locally cache both RBL´s. Proxmox can synchronize these blacklists locally to provide quality of service and speed up the query time.

3.4.4.1 Configuring local DNS blacklist caches

Some DNS blacklist providers offers data feed services. You can locally mirror blacklist

data making queries to remote DNS servers unnecessary. Proxmox can use local DNS blacklist caches of spamhaus.org and dsbl.org. Just set the IP address of your local mirror, or '127.0.0.1' to disable it (default). You can use your Proxmox Server to download the blacklists, but you can also use any other server within your network.

Note: Spamhaus data feed is a commercial service – additional license/account required. For details visit http://www.proxmox.com

HowTo: Synchronize DNS blacklist to the Proxmox server

Local sync is done via proxblsync, usually started via cron. Please log in to the console and configure the following:

crontab –e 11,41 * * * * proxblsync --spamhaus rsync1.spamhaus.org --dsbl rsync.dsbl.org -

-mailto root

Note: “11,41” stands for the minutes of each hour, please replace these values with the

one in your spamhaus datafeed license.

Next, configure the RBLDNS daemon configuration file:

nano /etc/default/rbldnsd RBLDNSD="- -r/var/lib/rbldns -f -b127.0.0.2 \

sbl.spamhaus.org:ip4set:sbl \ pbl.spamhaus.org:ip4trie:pbl \ xbl.spamhaus.org:ip4tset:xbl \ zen.spamhaus.org:ip4set:sbl \ zen.spamhaus.org:ip4trie:pbl \ zen.spamhaus.org:ip4tset:xbl \ list.dsbl.org:ip4set:dsbl"





Start the RBLDNS service:

/etc/init.d/rbldnsd start

Finally, redirect query to local mirror:

Figure 3-4 Enable local RLB cache – Spamhaus.org and Dsbl.org

3.4.5 Receiver Verification

Nowadays, e-mail domains are receiving a lot of e-mails to non-existing users. This could be up to 95 % of junk messages.

In short, this means for your systems:

Increased traffic on your internet connection Your e-mail server is handling junk e-mails instead of working for you High load on your scanners Slow overall performance and high costs

3.4.5.1 Proxmox Solutions

Proxmox can detect these e-mails to non-existing users on SMTP level, which means BEFORE the e-mails are transferred to your networks. In short, this means for your systems:

reduced traffic, up to 90 % Your internal e-mail server is now working for you again Reduced load on your scanners, 90 % less e-mails to analyze for spam and

viruses Good performance and costs




3.4.5.2 Enabling Verify Receivers

You can enable this option on the admin interface (Configuration/Mail Proxy/Options)

We recommend selecting yes (450). 450 means, that in the case of a short downtime of your internal mail server no messages are lost.

Note: Your internal e-mail server has to be reconfigured to reject unknown user. Proxmox is doing a short query to the internal e-mail server to check if the user is valid. For settings on Exchange 2003 SP2, see chapter 3.4.5.2.1 Settings for Exchange 2003 SP2

Figure 3-5 Enable Verify Receivers




3.4.5.2.1 Settings for Exchange 2003 SP2

You have to enable Recipient Filtering, please use the Exchange System Manager.

Figure 3-6 Exchange 2003: Filter recipients 1













3.4.5.2.2 Settings for Exchange 2007 SP1

First, make sure that you have the Exchange 2007 Anti-Spam agent. If you installed a typical one server installation, this is NOT installed by default. Microsoft provides an install script to manually install the Anti-Spam agent:

1. Open the Exchange Management Shell 2. cd “c:\program files\Microsoft\Exchange Server\Scripts” 3. .\install-AntispamAgents 4. Restart the Microsoft Exchange Transport service

Figure 3-10 Exchange 2007 SP1: Install Anti-Spam agent Now you can enable Recipient Filtering on the Anti-Spam agent, please use the Exchange Management Console.

Figure 3-11 Exchange 2007 SP1: Filter recipients 1




Figure 3-12 Exchange 2007 SP1: Filter recipients 2

4 Rule System The object-oriented rule system enables custom rules for your domains. It’s an easy but

very powerful way to define filter rules by user, domains, time frame, content type and resulting action.

Who - object

For TO and/or FROM Category Example: Mail object - Who is the sender or receiver of the e-mail?

When - object

Example: When is the e-mail received by Proxmox Mail Gateway?

What - object

Example: Does the e-mail contain spam?

Action - object

Example: Mark e-mail with "SPAM:" in the subject.

Every rule has got 5 categories (FROM, TO, WHEN, WHAT, ACTION) which can contain several objects. For example enable Archive Solutions with BCC Object (Blind carbon copy, recipients not visible in the "To" field) to Mailbox or to a Public Folder

FROM: Anybody TO: Anybody WHEN: Always WHAT: Mail

ACTION: BCC to Publicfolder

In most of the countries worldwide a company has to forward all e-mails to there employees this includes spam e-mails as well.




For example to send Spam mails in quarantine

FROM: Anybody

TO: Anybody WHEN: Always WHAT: Spam ACTION: Quarantine

With this kind of setup the receiver gets detailed Information about the Spam e-mails. Quarantine can be enabled just for existing LDAP groups or via BCC to Public Folders or

Mailboxes. At present the usefulness of e-mail is being threatened by three phenomena: spamming, pishing and e-mail worms. Spamming is unsolicited commercial e-mail. Because of the very low cost of sending e-mail, spammers can send hundreds of millions of e-mail messages each day over an

inexpensive internet connection. Hundreds of active spammers sending this volume of mail results in information overload for many computer users who receive tens or even hundreds of junk messages each day. E-mail worms use e-mail as a way of replicating themselves into vulnerable computers. The combination of spam and worm programs results in users receiving a constant drizzle of junk e-mail, which reduces the usefulness of e-mail as a practical tool.

To increase the efficiency of e-mail communications the use of anti-spam, anti-pishing and antivirus software is essential. With the deployment of Proxmox Mail Gateway you get the job done. Based on the design as software appliance one of the strengths of Proxmox Mail Gateway is its flexibility. It can be easy integrated in existing E-mail architecture. It’s compatible to every type of mail server or MTA (e.g. Microsoft Exchange, Lotus Domino, Postfix …). For example a virus protection looks like this:

FROM: Anybody TO: Anybody WHEN: Always WHAT: Virus ACTION: Block

Options range from simple spam and virus filter setups to sophisticated, highly customized configurations blocking certain types of e-mails and generating notifications.




4.1 Default Rules

4.1.1 Block Viruses

This rule blocks all incoming virus e-mail and informs the admin via e-mail notification.

Figure 4-1 Rule: Block Viruses

4.1.2 Virus Alert

This rule blocks all outgoing virus e-mail and informs the admin and sender via e-mail notification.

Figure 4-2 Rule: Virus Alert




4.1.3 Block Dangerous Files

This rule removes dangerous attachments from incoming e-mails (.vbs,.bat,.com, …)

Figure 4-3 Rule: Block Dangerous Files

4.1.4 Mark Spam

This rule identifies spam and modifies the spam level and the e-mail subject.

Figure 4-4 Rule: Mark Spam




4.2 Custom Rules Proxmox provides samples for custom rules to show the functionality. For support or help configuring rules see the Proxmox support forum at: http://www.proxmox.com/forum/ or contact a Proxmox partner.

4.2.1 Enable Spam and Virus quarantine

Activate or change the Spam and/or Virus rule with the existing action object “Quarantine”.

Figure 4-5 Add “Quarantine” action to rule “Mark Spam”

4.2.2 Enable Spam quarantine for just a selection of users

If you want to use the spam quarantine for specific users or a specific domain (and for the rest just “Mark Spam”), create a new WHO object containing these users or domains.

1. Create a new WHO object; give a name like “Quarantine Users” and add the users or domains to this object

2. Use the existing (inactive) rule “Spam Quarantine” and set higher priority than the “Mark Spam” rule (e.g. 81)

3. Add the WHO object “Quarantine Users” 4. Activate the rule

http://www.proxmox.com/forum/




Figure 4-6 Enable Spam quarantine for just a selection of users

4.2.3 Enable Spam quarantine for existing LDAP users

If you want to use the spam quarantine only for existing internal e-mail addresses, you can use the LDAP query “Existing LDAP”.

1. Create a new WHO object; give a name like “Existing LDAP address” and add the LDAP group “Existing LDAP address”

2. Use the existing (inactive) rule “Spam Quarantine” and set higher priority than the “Mark Spam” rule (e.g. 81)

3. Add the WHO object “Existing LDAP address” 4. Activate the rule

Figure 4-7 Create WHO object “Existing LDAP address”




Figure 4-8 Enable Spam quarantine for existing LDAP addresses




4.2.4 Block Spam e-mails with a score higher 10

The default setting marks Spam with a score higher 5 and delivers the e-mail to the user. With this additional rule, you can block Spam with a score higher 10 to reduce the

delivery of spam e-mails to the user.

1. Create a new “What Object”, give a name, e.g. “Spam Level 10” Figure 4-9 2. Add “Spam Filter” to the Object Figure 4-10 3. Set the Set Spam Filter to Level 10 Figure 4-11 4. Add new Rule, give a name, e.g. “Delete Spamlevel 10”, Set Priority to 81 (higher

than the “Mark Spam” rule!, set Direction to “In” Figure 4-12 5. Add What Object “Spam Level 10” to the rule Figure 4-13 6. Add Action Object “Block” to the rule Figure 4-14 7. Final review (still inactive) Figure 4-15 8. Activate rule Figure 4-16

Figure 4-9 Add new What Object




Figure 4-10 Add Spam Filter to a What Object

Figure 4-11 Set Spam Filter to Level 10




Figure 4-12 Add new Rule

Figure 4-13 Add What Object to a Rule




Figure 4-14 Add Action Object to a Rule

Figure 4-15 Final Review of Rule (still inactive)




Figure 4-16 Activate Rule

4.2.5 BCC object – An simple archive solution

If you need to archive e-mails it’s useful to send a copy to a special mailbox. If you have

Microsoft Exchange, you can also send a copy to a mail enabled public folder.

1. Create an Action Object: “Add BCC Object”, name it “BCC to Archive Public folder or Mailbox”

2. Under “Receiver”, type the e-mail address of the public folder/Mailbox 3. Click on an already existing rule or create a new one 4. Add Action Object “BCC to Archive Public folder or Mailbox” to the rule

How to create a Mail Enable Public Folder under Exchange 2000/2003?

1. Create a public folder in Exchange (Exchange System Manager or via Outlook) 2. "Mail enable" the public folder via Exchange system manager – right click an

select “Mail Enable” 3. Wait a few minutes, Exchange creates the e-mail address 4. Right click the folder an check the e-mail address (or change it, if you want),

remember e-mail address 5. Set appropriate client permission (note: anonymous must have the right to create

items) 6. Optional: Set age limit: select “Limits” and set the age limit to 90 days (all

messages older than 90 days will be automatically deleted)

4.2.6 Block Video and Audio Attachments

1. Create a new rule, e.g. “Block Multimedia Files”, define direction and set priority 2. Add What Object “Multimedia” to the rule




3. Add Action Object “Block” to the rule 4. Final review (still inactive) 5. Activate the rule

4.2.7 Add Admin Notification to Rules

If you block mails it’s useful to inform the Proxmox Admin.

1. Click on the desired rule 2. Add the “notify Admin” action to the rule

4.2.8 Preventing directory harvesting attacks with LDAP object

The LDAP group object “Unknown LDAP address” can be used to prevent directory harvesting attacks. The Mail Gateway can check incoming e-mail addresses against valid e-mail addresses in your organization.

1. Create a new “WHO Object”, give a name, e.g. “Unknown LDAP” 2. Add an “LDAP Group” to the Object, select “Any profile” and “Unknown LDAP

Address”, then click save. 3. Now you can test your object against e-mail addresses. If you type an unknown

e-mail address, it should be member of the Unknown LDAP group. If you type a valid e-mail address, it should not be member.

4. Add new rule, give a name, e.g. “Unknown LDAP”, set priority to 85 (higher than the “Mark Spam” rule, set direction to “in”

5. Add the WHO object “Unknown LDAP” from above to the rule (as “to”)

6. Add the WHAT “Spam” to the rule 7. Add the ACTION object “block” (for testing, just add a notify to see results – be

careful with block action) 8. Final review (still inactive) 9. Activate the rule

Note: Add always the “Spam” object – because most directory attacks are also spam. So you just block attacks from spammers and you still are able to send NDR to people just mistyping an e-mail address.




Figure 4-17 Unknown LDAP address rule

4.2.9 Block Video and Audio Attachments for LDAP Groups

The LDAP groups can be used to apply special settings to groups.

Most people like sending joke videos and audio files via e-mail – this grows up your users mailboxes. On the other side, you do not want to block these funny things for everybody. We assume you have a LDAP group called “Staff”.

Create a new “WHO Object”, give a name, e.g. “Staff” Add “LDAP Group” to the Object, select “your LDAP Profile” and select “Staff” from

the dropdown menu, click save. Now you can test your object against e-mail addresses Add new rule, give a name, e.g. “Block Multimedia for Staff”, set priority to 70,

set direction to “in”, click save Add the WHO object “Staff” from above to the rule (as “to”) Add the WHAT “Multimedia” to the rule

Add the ACTION object “Remove Attachments” Final review (still inactive) Activate the rule

Note: Removed attachments from e-mails are replaced with a text file.




Figure 4-18 Block video and Audio attachment for LDAP group “Staff”




5 Proxmox HA Cluster – High availability We are living in a world where e-mail becomes more and more important - failures in e-mail systems are just not acceptable. To meet these requirements we developed the

Proxmox HA (High Availability) Cluster. The Proxmox HA Cluster consists of a master and several nodes (minimum one node). Configuration is done on the master. Configuration and data is synchronized to all cluster nodes over a VPN tunnel. This provides the following advantages:

centralized configuration management fully redundant data storage high availability high performance

Proxmox uses a unique application level clustering scheme, which provides extremely good performance. Special considerations where taken to make management as easy as possible. Complete Cluster setup is done within minutes, and nodes automatically

reintegrate after temporary failures without any operator interaction.

Figure 5-1 Proxmox HA Cluster with load balanced MX records




5.1 Load Balancing with MX Records It’s quite simple to set up a high performance load balanced mail cluster using MX records. You have to define two MX records with the same priority. You need to have 2 working Proxmox Mail Gateways (mail1.example.com and mail2.example.com), each having its own IP address (the rest of the setting should be more or less equal, i.e. you can use backup/restore to copy the rules). We recommend adding reverse lookup entries (PTR records) for those hosts. Many e-mail systems nowadays reject mails from hosts without valid PTR records. This is all you need. You will receive mails on both hosts, more or less load-balanced

(round-robin scheduling). If one host fails the other is used.

Figure 5-2 Load balancing via MX Records




5.2 Multiple Address Records Using several DNS MX record is sometime clumsy if you have many domains. It is also possible to use one MX record per domain, but multiple address records:

Figure 5-3 Load balancing Multiple Address Records

5.3 Using third party Firewall features Many firewalls can do some kind of RR-Scheduling (round-robin) when using DNAT. See your firewall manual for more details.




6 Hardware selection and Virtualization Proxmox always needs a dedicated PC or server hardware. Alternative, Proxmox can be run under VMware™, OpenVZ and Proxmox VE.

Proxmox delivers prebuilt Virtual Appliances for:

Proxmox VE (http://pve.proxmox.com) VMware™ OpenVZ

Also known to work (Intel VT or AMD-V needed):

Virtualbox XEN (Full virtualized) Citrix XenServer (Full virtualized) Parallels Server Virtualbox

Hyper-V For best performance please use physical hardware or OS virtualization like Proxmox VE (OpenVZ).

6.1 Physical Hardware See http://www.proxmox.com for certified hardware. For maximum performance we recommend:

Hard disks SAS Disk (15.000rpm), Hardware Raid with battery backup and cache enabled

CPU Two Quad Core Xeon (5xxx)

RAM 4 GB ECC

6.1.1 Certified Hardware

The latest certified hardware list is published on http://www.proxmox.com.

6.2 Proxmox VE (http://pve.proxmox.com) The Mail Gateway is available as a certified Virtual Appliance for Proxmox VE. For all details see http://pve.proxmox.com/wiki/Proxmox_Mail_Gateway

6.3 VMware™

Proxmox runs perfectly under VMware™. For quick deployment Proxmox delivers a ready to run, preconfigured and certified Virtual Appliance. Installation from the ISO-Image is also fully supported and gives the possibility for custom settings, optimized for the VMware™ Host. Proxmox 2.3 and later supports VMware™ para-virtualization (Kernel 2.6.27) and we deliver a prebuilt VMware Tools package for installation

(already included in the Appliance).

http://pve.proxmox.com/



http://pve.proxmox.com/

http://pve.proxmox.com/wiki/Proxmox_Mail_Gateway




6.3.1 Settings for VMware™ ESX, ESXi and vSphere

Proxmox dynamically adapts the number of processes referring to the given memory to maximize performance. This means, if Proxmox runs on a machine with 1 GB memory it uses 1 GB of memory. A VMware™ host can swap memory between guests and if configured, the host can show more physical memory to the guest as available by swapping to disks. This leads to very poor performance. While memory overcommit is possible, for optimal operation you should never assign more memory to virtual machines than is available on the host. For more details see VMware documentation on http://www.vmware.com.

6.3.1.1 Settings for the Proxmox Mail Gateway Virtual Machine

6.3.1.1.1 RAM settings

The minimum memory for running Proxmox Mail Gateway is 512 MB RAM.

6.3.1.1.2 VMware Tools

Proxmox precompiles the VMware Tools components for easy installation. Please visit the support forum for detailed instructions and downloads. http://www.proxmox.com/forum/.

6.3.1.1.3 Enable VMI Paravirtualization

Figure 6-1 Enable VMI Paravirtualization for Proxmox Mail Gateway on ESX

http://www.vmware.com/





6.3.1.1.4 Enable time synchronization

Figure 6-2 Enable time synchronization on ESX/ESXi

6.3.2 Settings for a VMware™ Server 2

Proxmox dynamically adapts the number of processes referring to the given memory to maximize performance. This means, if Proxmox runs on a machine with 1 GB memory it uses 1 GB of memory.

A VMware™ host can swap memory between guests and if configured, the host can show more physical memory to the guest as available by swapping to disks. This leads to very poor performance. While memory overcommit is possible, for optimal operation you should never assign more memory to virtual machines than is available on the host. For more details see VMware documentation on http://www.vmware.com.

6.3.2.1 Host memory settings

Always choose this option: “Fit all virtual machine memory into reserved host RAM” Strictly apply the reserved memory limit set in the top of the panel. This setting imposes the tightest restrictions on the number and memory size of virtual machines that can run at a given time. Because the virtual machines are running entirely in RAM, they have the best possible performance.

http://www.vmware.com/




Figure 6-3 Memory settings for VMware Server 2 Host

6.3.2.2 Settings for Proxmox Mail Gateway Virtual Machine

6.3.2.2.1 RAM settings

The minimum memory for running Proxmox Mail Gateway is 512 MB RAM.

6.3.2.2.2 VMware Tools

Proxmox precompiles the VMware Tools components for easy installation. Please visit the support forum for detailed instructions and downloads. http://www.proxmox.com/forum/.

6.3.2.2.3 Enable VMI Paravirtualization





Figure 6-4 Enable VMI Paravirtualization for Proxmox Mail Gateway

6.3.2.2.4 Enable time synchronization




Figure 6-5 Enable time synchronization on VMware Server 2 Host

6.4 OpenVZ OpenVZ is an Open Source Operating System-level server virtualization solution, built on Linux. For details about OpenVZ, please visit http://openvz.org/. OpenVZ is also used in Proxmox VE (http://pve.proxmox.com). Main advantage from Operating System-level server virtualization is minimum overhead which leads to maximum performance. Proxmox runs on OpenVZ quite as fast as on physical hardware with all advantages from virtualization. OpenVZ supports online

migration from a running Proxmox from one hardware node to another without downtime. For running Proxmox on OpenVZ, we launched a wiki page on:

http://openvz.org/




http://wiki.openvz.org/Proxmox_Mail_Gateway_in_VE For online backups of a running OpenVZ, we developed vzdump: http://wiki.openvz.org/Backup_of_a_running_VE_with_vzdump

http://wiki.openvz.org/Proxmox_Mail_Gateway_in_VE

http://wiki.openvz.org/Backup_of_a_running_VE_with_vzdump




7 Troubleshooting and technical support Use the moderated Proxmox support forum or contact a Proxmox partner for their support offerings.

All information: http://www.proxmox.com Email support: [email protected]



mailto:[email protected]




8 Table of figures Figure 2-1 System without Proxmox Mail Gateway ............................................ 6 Figure 2-2 Incoming e-mail with Proxmox Mail Gateway ................................... 6 Figure 2-3 Outgoing with Proxmox Mail Gateway .............................................. 7 Figure 2-4 Incoming default port settings (port 25) .......................................... 8 Figure 2-5 Outgoing default port settings (port 26) .......................................... 8 Figure 2-6 Incoming alternative port settings (port 26) .................................... 9 Figure 2-7 Outgoing alternative port settings (port 25) .................................... 9 Figure 2-8 Proxmox in DMZ ..............................................................................10 Figure 2-9 Multiple e-mail servers ....................................................................11 Figure 3-1 Use local DNS Cache ........................................................................12 Figure 3-2 Mail proxy whitelist .........................................................................13 Figure 3-3 Enable RBL checks ...........................................................................14 Figure 3-4 Enable local RLB cache – Spamhaus.org and Dsbl.org .....................16 Figure 3-5 Enable Verify Receivers ...................................................................17 Figure 3-6 Exchange 2003: Filter recipients 1 ..................................................18 Figure 3-7 Exchange 2003: Filter recipients 2 ..................................................19 Figure 3-8 Exchange 2003: Filter recipients 3 ..................................................20 Figure 3-9 Exchange 2003: Filter recipients 4 ..................................................20 Figure 3-10 Exchange 2007 SP1: Install Anti-Spam agent ................................21 Figure 3-11 Exchange 2007 SP1: Filter recipients 1..........................................21 Figure 3-12 Exchange 2007 SP1: Filter recipients 2..........................................22 Figure 4-1 Rule: Block Viruses ..........................................................................24 Figure 4-2 Rule: Virus Alert ..............................................................................24 Figure 4-3 Rule: Block Dangerous Files ............................................................25 Figure 4-4 Rule: Mark Spam .............................................................................25 Figure 4-5 Add “Quarantine” action to rule “Mark Spam” .................................26 Figure 4-6 Enable Spam quarantine for just a selection of users ......................27 Figure 4-7 Create WHO object “Existing LDAP address” ...................................27 Figure 4-8 Enable Spam quarantine for existing LDAP addresses .....................28 Figure 4-9 Add new What Object ......................................................................29 Figure 4-10 Add Spam Filter to a What Object ..................................................30 Figure 4-11 Set Spam Filter to Level 10 ............................................................30 Figure 4-12 Add new Rule ................................................................................31 Figure 4-13 Add What Object to a Rule .............................................................31 Figure 4-14 Add Action Object to a Rule ...........................................................32 Figure 4-15 Final Review of Rule (still inactive) ...............................................32 Figure 4-16 Activate Rule .................................................................................33 Figure 4-17 Unknown LDAP address rule ..........................................................35 Figure 4-18 Block video and Audio attachment for LDAP group “Staff” ............36 Figure 5-1 Proxmox HA Cluster with load balanced MX records ........................37 Figure 5-2 Load balancing via MX Records ........................................................38 Figure 5-3 Load balancing Multiple Address Records ........................................39 Figure 6-1 Enable VMI Paravirtualization for Proxmox Mail Gateway on ESX ...41 Figure 6-2 Enable time synchronization on ESX/ESXi .......................................42 Figure 6-3 Memory settings for VMware Server 2 Host .....................................43 Figure 6-4 Enable VMI Paravirtualization for Proxmox Mail Gateway ...............44 Figure 6-5 Enable time synchronization on VMware Server 2 Host ...................45




9 Appendix Reference document: Mail Gateway AdminGuide

You can download the latest version from www.proxmox.com

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