Sunday, January 22, 2012

SMTP NAT with Sendmail

This post is closely related to my previous one. Big difference is that in this case company we bought had Lotus Notes based email system that had to be kept running concurrently with new common email platform for several months. Well, actually it is still running to some extent over 4 years later but that's another story.

Simple fetchmail config

Few hours ago you got called to meeting with your boss. You were told that company you're working for just bought another firm and everything needs to be integrated ASAP starting with unifying email addresses.

Thursday, January 19, 2012

Reliable IP over multiple unrealiable IP links with Linux and Strongswan

Some time ago I wrote about how to make multiple unreliable Internet connections function like single reliable Internet connection. That was done using OpenVPN and some iptables trickery. This time we're going to do same without OpenVPN and without iptables.

Wednesday, January 18, 2012

Linux multipoint GRE tunneling

Here's another interesting little known feature of Linux kernel GRE support.

Layer 2 over Layer 3 using Linux built-in features

Often it's not necessary to encrypt traffic when tunneling L2 network over L3 in corporate environment. I hear, you say use OpenVPN, tinc, gvpe, n2n etc. Now, did you know that there's easy built-in solution that has been part of Linux kernel since 2.6.29? If you need encryption just use IPsec to protect GRE traffic.

Tuesday, January 10, 2012

Fixing broken VMware vSphere 5 VMDK disk image

These are kind of "last resort" fixes if all normal ways fail to resolve problem. No guarantees. Worked for me...

    Monday, January 09, 2012

    Planet WNAP-7300 (Zcomax ZCN-1523H-5) with OpenWrt r29664

    It turned out to be just like I suspected, Planet WNAP-7300 (at least with firmware "2.0.3(PL)4") is exactly same device as Zcomax ZCN-1523H-5. Atheros AR7240 rev. 2 at 350MHz, Atheros AR9280 rev 2 5GHz radio, 32MB RAM, 8MB Flash and two 10/100 Ethernet ports. Therefore it works with Zcomax OpenWrt firmware. Bridge performance seems acceptable, around 70Mbit/s real world in bridged mode and 60Mbit/s if OpenWrt is doing NAT. With around 25 meters nearly line-of-sight performance is ~40Mbit/s. All tests uni-directional TCP (FTP/HTTP) with no other traffic than ICMP echo going on at the same time.

    Using dy.fi dynamic DNS with OpenWrt

    Didn't see this documented anywhere so here it is. How to use Finnish dy.fi dynamic DNS service with OpenWrt router.

    Sunday, January 08, 2012

    Running Mac OSX Lion 10.7.2 with VMware Workstation 8.0.1 for Linux

    Host system configuration:
    Intel Core2Duo 6300 w/VT
    CentOS 5.7 x64
    VMware Workstation 8.0.1


    Saturday, January 07, 2012

    Strongswan 4.6.2dr3 on Ubuntu 12.04 alpha 1

    For some reason latest Strongswan version for Ubuntu is still 4.5.1. See below how to compile and package latest 4.6.2dr3. Not pretty, but works for me when testing new version.

    Thursday, January 05, 2012

    Bridging networks with OpenWrt (r29611) using L2TPv3

    As OpenWrt Wiki lacks this particular example (there's other L2TPv3 examples) I guess better I document it somewhere.

    Unpacking Planet Tech. Corp. WNAP-7200 and WNAP-7300 wireless APfirmware

    Instructions were tested with Ubuntu 11.04.