Mail Server Hardening Tips
Aug 15, 2008
We have a linux server running cPanel/WHM and using Exim for mail, we're also using SpamAssassin to label messages as spam. I have made a few modifications to settings and installed things like DomainKeys, but am wondering if I am doing enough.
My objectives are to:
1) Prevent mail users on the server from being inundated with spam, and/or be able to effectively manage any spam that does come through.
2) Ensure that messages that my mail users send out remains as highly deliverable as possible.
3) Make it difficult for third parties to exploit my mail server for their own spamming needs.
Are there any good tutorials out there on this stuff that should at least cover some of my bases? Where should I begin? The only thing preventing me from hiring out the work to someone else is that I'd like to learn how to do it myself.
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Jan 30, 2009
Customer wants to move his website in-house along with his email. The hardware guy installed a windows 2003 64-bit exchange server. I logged in with logmein and created a directory c:Inetputwwwroot hewebsite. Copied iisstart.html to the new dir. Put the company name in the iisstart file. Opened IIS6. Went to properties of the default website and pointed to the new directory on the home dir page. Added iisstart.html the Documents page and moved it to the top. Closed everything. Opened Internet Explorer 7 and put in http://localhost. All worked well. Brought up the new start page. Opened IE7 on my pc and put there ip address in and it also brought up the new webpage (tested the port 80 in the router). Said we were ready to go.
The hardware guy sent me an email stating that he was having problems with the 64-bit version and took the server back to the 32-bit version of windows exchange server. I logged back in with logmein and followed the same exact steps as above but it will not show the new webpage. Am getting a page not found error.
I have done the above on several 2003 servers and several xp pro machines. Always works.
Have done one 2003 exchange server. Went to a couple of those servers and made sure the default website settings were exactly the same as the ones that work. Still no help.
Downloaded an iis6 troubleshooting program from microsoft but cannot locate the error. I have been studying the II6 documentation and 2003 exchange server documentation. Went thru all the tutorials in google on iis6 and exchange I can find no help.
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Apr 16, 2009
So I did something terribly dumb early this AM...go me...and I had to reinstall. Yes, it was that bad. Kernel panics, a hoarked up bootloader, nothing in the execution path, etc. Let's just say that between the 2.6.18-128.el5 kernel (I've been reading that there are a lot of reports of file corruption after this update, something I saw as well...) and yum doing something it wasn't supposed to, I'm having to start over. Thank goodness for backups. Anyways, to my questions:
CentOS 5.3 64-bit, clean install, no CP yet. I'm trying to get the base OS clean, simple and hardened before I put DA on there again and restore my websites but I have a few questions since I'm a network dork and normally pay for people to do the extended server hardening for me.
/etc/passwd/ ....
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Feb 6, 2008
I have a dedicated server, and want to make it safe...
I once had a HOWTO to do that with things as APF and such, but is there some howto out there that is recent?
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Sep 15, 2007
What a few things you would do to boost the security of your VPS? So far I have securing/restricting SSH access, installing chkrootkit and putting up a firewall. Any other things I should do?
Just noticed I put VPS Server Hardening, should be VPS Hardening
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Oct 25, 2007
There are many people who sell server hardening for windows and linux and all the packages are pretty much the same. I don't want to give anyone outside access to my server no matter how much they claim to be good, fact is once it's out, it's out.
Is there an online resource with some sort of check list and links for a quality server hardening for windows and linux servers?
I.E. install this, install that, configure this?
Seems that do it yourself is worth the training and $100
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Jul 22, 2007
Is there a guide or check list of settings to make on a new box that I can follow to lock it down?
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Nov 23, 2007
1. I don't use nor will I EVER use cPanel (royal POS in my opinion). I might, however, have DirectAdmin installed (not sure yet)
2. CentOS 5, 64-bit edition
3. Apache 2.2 latest, MYSQL 5.1 latest, PHP 5.2 latest
I usually use appears to be super busy and just not able to get the job done. No slight on him, he has a busy work schedule. So I'm looking to go outside of my comfort zone and see other companies to use. I don't think I can use Platinum as I outright refuse to even discuss cPanel as an option. If I want an underperforming, unsecure and incompatible web and database server, I'll run Windows.
So I'm looking for the usual end-to-end hardening package. I'm too lazy to do it myself and I'll forget to do something. Any recommendations out there in WHT land?
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Dec 24, 2008
Other than anti-virus
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Oct 29, 2009
We have discussed all the basic methods of securing and hardening the server. Lets leave all the basic and general server securing and hardening I have started this to get advance knowledge in securing and hardening of the server so that it will usefull for all the person So i request all to provide all the vaulable tips and suggestions in advance securing and hardening of linux servers I welcome all the comments related to advance securing and hardening of linux servers.
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Jul 2, 2007
I'm considering the advantage of using some of my hosting space/accounts to offer an affordable reseller package. (Yes, I do have permission to do this)
Anybody got advice/tips on how you've/would set this up?
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Apr 6, 2007
I currently have a vps server from GIGEServers, running at 512mb of dedicated and 1024mb spike it seems like apache is using alot of resources, does anyone know of a less hog, or tips on tweaking it, and the same for mysql server any tips on tweaking.
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May 27, 2007
We're currently testing Postini after checking with Message Labs, etc and it seemed that Postini was the most highly recommended out of all of them. We shall see, as there does seem to be ALOT that get past their filters with spam level filtering set at their most sensative level.
However, what could I do for accounts with Hosting Firms. We have a couple on Pair, and while they use SA, their filters doesn't seem to be really effective at all. Users can come in over the weekend, and have 5 valid emails out of 200 junk......
BTW, has anyone used any of the spam appliances out there lately.
We tested them about 1.5 years back and none were really effective
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Nov 8, 2008
Does any one know of any good articles/tutorials on how to harden PHP and Apache on a cPanel VPS?
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Jan 12, 2008
I want to restrict ALL port 25 and port 26 email only to users who authenticate first.
I thought it came this way on Cpanel boxes, but yet there's a ton of crap being relayed through my box and getting me on tons of blacklists.
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Mar 19, 2009
where I can find a guide or how-to to hardening Debian Lenny web server (a xen vps one)?
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Nov 27, 2007
while the ELS script looks pretty sexy on paper, it appears that the hardening of the /tmp and /shm is fairly problematic on CentOS 5 systems. Apparently the entire process is mucking up /etc/fstab and yes, I know, I'm being 100% lazy by using a script...so sue me.
Wanted to see if anyone had any success or complete disaster stories running ELS on a CentOS 5, preferrably 64-bit, system in the past few months and would be willing to share their experience. There's more than just the filesystem hardening in it and I'm looking for some of the other aspects but that seems to be the reoccuring nightmare scenario people are having.
For those wondering what ELS is, here's a good (and bad) discussion about it on the DirectAdmin forums. I'm sure there's others but this is where my search started.
[url]
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Mar 26, 2009
Since this got lost (google cache of thread discussion so far)
[url]
im reposting because i think it was an interesting discussion.
I'm setting up a cpanel server for the first time. I was wondering if i could harden the default cpanel permissions for the user folders in /home The idea is to prevent users viewing each others files. Please don't suggest the php open_basedir option as its not secure and doesn't work with cgi based file browsers.
Note I'm using suexec/suphp.
currently new cpanel users folders are created with
group and user ownership and the permissions 755
I was thinking if i changed this to 711 would this break anything?
Could i lock this down even more by changing the group ownership to "nobody" and thus have permissions 710.
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Jan 26, 2007
I am compiling a list of security hardening procedures which should be performed to a server, with the goal of coming up with a comprehensive list of hardening procedures which should be implemented.
The following lists the details I have compiled so far. Please feel free to contribute additional hardening tips so we may come up with a full and thorough list:
Install mod_security
Install mod_evasive
Install mod_limitipconn
Install APF
Install BFD
Install PRM
Install SIM
Install portsentry
Install chkrootkit and configure reporting cronjob
Install rkhunder and configure reporting cronjob
Install snort
Install tripwire
Install libsafe
Install mail header patch to identify cause of spam sent through nobody
Limit compiler and fetch utilities access to root only
Correct folder permissions to prevent directory transversal
Remove unneeded OS packages
Upgrade kernal to latest OS release
Ensure MySQL password is set
Ensure OpenSSH protocol is only using protocol 2
Ensure cannot SSH directly to root. Must SSH to admin first.
Enforce noexec & nosuid on temporary directories /tmp and /var/tmp
Disable used services
Disable DNS recursion
Disable IP source routing
Disable IMCP redirect acceptance
Disable certain php functions (system, exec, shell_exec)
Enable IP spoofing protection
Enable Spoofing protection
Enable syncookie protection
Enable misc. sysctl settings
Harden host.conf
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May 3, 2007
I've just ordered my new Windows 2003 server with 49Pence.com and will be taking "delivery" of it once they have commissioned it.
Anyway, I would appreciate some advice on how to secure it. I have been used to the luxury of a hardware firewall, but budgetary constraints mean I will have to rely upon a software firewall (something that scares me a little). It will be running our company websites, MSSQL and MDaemon mailserver.
I am not sure exactly how the server will be delivered, but I assume it will arrive fully patched with Remote Desktop access, and Windows Firewall installed.
First question: Is Windows Firewall sufficent? I am more used to configuring firewalls with Ports/Protocols/IP's rather than "applications". I also understand that Windows Firewall cannot restrict access to specific IP's.
I read that IPSec / TCP Filtering should also be used. I've looked at various links and have an idea how to do this, but I do not want to make a mistake and get "locked out". I saw a post saying that during testing they set up a scheduled job to reset the IPSec policies every x minutes so that they can log back in if they do make a mistake. How would this be done (in terms of IPSec) .. or is this a matter of stopping a service?
If I go with another software firewall, is there an easy way to install remotely without getting locked out of the Remote Desktop? KVM over IP is a charged by the hour.
It is "safe" to leave Port 3389 open and rely upon passwords (and potentially IPSEC IP policies), or should I administer by VPN?
If so, it seems that in order to create a VPN connection on the server, it requires that the Windows Firewall is shut down (at least on my test server here). Obviously this is something I don't want to do!
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Jul 2, 2008
I getting this error when our clients are sending mail from outlook but they are able to send mail from webmail.
we are using exim mail server and whm . i can't understand where is problem , anybody can help me ?
Sending' reported error (0x800CCC6A) : 'Your
outgoing (SMTP) e-mail server has reported an internal error. If you
continue to receive this message, contact your server administrator or
Internet service provider (ISP). The server responded: 451 Please try again
later.
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