PPTP Vpn through a Linux IpTables/Netfilter firewall

I spent some time configuring a pptp vpn for one of our offices yesterday, but it kept failing to connect during testing. Each failure generated these errors in the firewall (the one I was Vpn-ing too) log.

pptpd[9078]: GRE: Bad checksum from pppd.
pptpd[9078]: CTRL: Received PPTP Control Message (type: 15)
pptpd[9078]: CTRL: Got a SET LINK INFO packet with standard ACCMs
pptpd[9078]: GRE: read(fd=7,buffer=80505a0,len=8260)
 from network failed: status = -1 error = Protocol not available
pptpd[9078]: CTRL: GRE read or PTY write failed (gre,pty)=(7,6)

As my comp.sci instructor would say, "Bad Times".

The vpn connection worked from a direct-internet-connected host, so logically the VPN setup was probably right. Here in the office I am behind a Linux IpTables firewall, and I deduced that it was probably the issue. Nothing was set to block the GRE protocol though, so I was a little puzzled.

I found this TLDP post (Do not bother reading it...) on how to make pptp work through iptables. Ah-ha! It was the firewall. Then I realized that documentation was ancient. By Ancient I mean it refers to the 2.0 and "new" 2.2 kernel. The current Linux kernel is > 2.6! eep! It was probably translated from some obscure dead language it is so old.

Anyway, the solution is much simpler... Iptables has a module that allows pptp to pass through NAT. My tale of woe happily resolved with this command.

modprobe ip_nat_pptp

One more useful tidbit. You can see a list of available IpTables modules with this command..

locate netfilter | grep .ko

Good Luck,
-Ellie

Installing Exchange 2007 on a single Server 2008 in an existing Windows 2003 domain

We are working on an Exchange migration.

By we, I mean I. :(

The scenario is everything on one server, with replication to our remote DR site. The users are 95% remote-via-internet users using RPC over HTTP. We are consolidating from a hegemony of SBS servers, Postfix, and outsourced providers.

Lessons learned in training.
Prerequisites are Powershell and IIS.
There are no send connectors by default.
Run setup /prepareAD
Requires x64 architecture.

Lessons learned by doing.
"Actual" Prerequisites...
Roles .. IIS Defaults PLUS
- IIS Metabase compatibility
- IIs 6 Management Console
- IIS 7 Dynamic Content Compression
- IIS 7 Basic Authentication
- IIS 7 Windows Authentication
- IIS 7 Digest Authentication
Features..
PowerShell
Active Directory Management Tools
RPC/HTTP Proxy

Setup /preparead doesn't actually work. Just run setup.
Right-click on setup and select Run as Administrator

"Things that would have been relevant to me yesterday."
A wildcard certificate (*.foo.com) will NOT work for Outlook Anywhere.
A multi-host "UCC" certificate is $200-$300.

The MS Exchange System Attendant is not set to Auto-start.
...RPC/HTTP requires the system attendant.

RPC/HTTP only listens on the IPV6 interface by default.
...Comment out the [:::] localhost line in the hosts file to fix it.
... ... Unchecking the IPV6 protocol box does NOT fix it.

Autodiscover is good!
... Autodiscover.foo.com should be one of the names on your UCC certificate

Exmerge is no more!
... and export-mailbox only works on the 32 bit version of the exchange tools, ergo it must be installed on a different box.

http://www.testexchangeconnectivity.com
... Web-based tests for exchange connectivity. Beta by Microsoft
... ... Use the back button and you get an ugly exception error.
... ... ... Dark green on blue captcha is a bitch for color-blind people.

I now have one mailbox up. Happy happy. :D

Only 650 to go. :(

-ellie

Removing drives from a dead Windows Cluster

For reasons too painful to explain, one of my Windows SQL clusters failed. Badly. I was able to remove the system from the cluster and take over the drives in the SCSI enclosure with this command.

"cluster node /forcecleanup"

I spool the backups to a local disk before shipping them to another server, and that command got the backups where I could copy them off before rebuilding the cluster. Woot....

-ellie

ActivePerl - The specified CGI application misbehaved by not returning a complete set of HTTP headers.

Today a friend called with a problem. He move this ASP/Perl website to a new server and now it didn't work.

Yes, that's right.. Perl AND Asp. Any theories about the emotional stability of the designer should be thought quietly to oneself. lol..

Loading the process.pl page gave this friendly error message.

Premature end of script headers:
Internal Server Error: 500 internal server error
The specified CGI application misbehaved by not returning a complete set of HTTP headers.

My first thought was the app was throwing some error message back, causing IIS to choke. The problem was that it didn't give us a useful (actionable) error message.

Looking at the program's code, it was writing out to a text file and didn't have permissions to write. We fixed that, but it still failed with the same error.

I looked in the (9,000 line) include.pl file trying to see which modules it was loading. That probably would have worked except the code caused me to briefly lose consciousness. I hate it when that happens.

Google saved me. One of the modules in CGI:: has the ability to return fatal errors to the browser. Here is the magic return-a-useful error incantation.

use CGI::Carp qw(fatalsToBrowser);

As it turns out, the application wanted the Mail::Sendmail module. We installed it and viola, the site worked. Time for a diet coke. Life is good.

Great Plains Integration Manager SP4 Bug

It looks like a bug creeped into the SQL optimized SOP Integration with Integration Manager service pack 4. After the service pack is applied all the line items on our SOP invoices have a 0 (zero) fulfilled quantity.

Argh, Another ticket.

-ellie

SQL Injection? No, I don't like needles, thanks.

Okay, so I like to read a lot. Like.. a lot. So I was reading Advanced SQL Injection In SQL Server Applications about a week after I read Google Hacks. The little lightbulb went off. Could it really be that easy? Could it?

In less time than it took to write this post, google (inurl:select inurl:where inurl:from) gave me 460 pages of results. About 20% or so look vulnerable to injection attack. A slightly modified query gives 496 matches for unprotected, non-passworded, wide open hey-look-it-is-Christmas phpMyAdmin sites.

O
M
G

I had to get that out of my system. I'm better now.

-Ellie

Funambol

A little more than a year ago, I wrote about ScheduleWorld, a free and open source place to sync Contacts and Calendars with a wireless device. The technology worked, but the setup was painful.

Fast forward to today. Another open source company, Funambol, has stepped up to the plate, pointed to center field, and driven the ball out of the park. I was able to setup a FREE account on my.funambol.com and sync my Sprint PocketPC in under 10 minutes. If all you wanted to do was backup your contacts and calendar, you'd be done. ...And it will push-sync your email too! That's right.. all the parts of a blackberry enterprise server that you use, compatible with a multitude of handsets, for free. And it you don't trust Funambol with your data, they'll give you the server software. For free.

But wait, there is more.

A "normal" user would pop in the Outlook plugin, enter the funambol username and password and be done.

As a "not-normal" linux person, I used SyncEvolution (free, open source, not made by funambol). It wasn't terribly difficult, but the config files would likely scare off any novice users. It let me push my contacts/calendar from Evolution. These instructions were really helpful, with one correction and one addendum. The "stable" and "main" in the apt repository line are lowercase and case sensitive. Also, step 6 didn't apply to me as I used the default calendar, note, and address book names.

But wait, there is more.

I flipped the phone's funambol client to scheduleworld, pulled those contacts down, flipped it back to funambol, and uploaded them.

The moment of truth..

It worked.

I now have all my contacts from my original blackberry, the treo, evolution, Outlook on my old Pc, all on my phone!

Thank you Funambol. the portal site is awesome... It is fast, responsive, pretty, and feature rich. The outlook, windows mobile, and blackberry plugin clients work great.

Thank you Funambol, and thank you open source.

-ellie