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Posted at 05:11PM Mar 05, 2012 by Carsten in Operating Systems  |  Comments[0]

Spring cleaning MacPorts

The MacPorts projects offers a fine, easy way to install Unix tools and applications on MacOS X. Over time however, MacPorts can accumulate amounts of dead data, as when applications get updated, the old versions stay until they are removed manually. In addition, after compiling a port from source, both the source and the intermediate object code remains on the harddisk.

Two commands can spring clean the MacPorts installation.

sudo port clean --all installed

sudo port -f uninstall inactive

Running these two commands can free up some gigabyte of space on a harddisk (depending on the amount of MacPort applications installed).

Posted at 10:23AM Apr 18, 2011 by Carsten in Operating Systems  |  Comments[0]

Managing the MacOS X IPv6 firewall

MacOS X (10.3 and up) contains an IPv6 firewall (ip6fw), which has been inherited from FreeBSD and the KAME project. However there are no configuration or startup scripts, nor any other support available in a stock MacOS X system to manage this firewall.

The script presented here will read a firewall configuration from '/etc/ip6fw.conf' and will apply the IPv6 firewall rules to the MacOS X firewall.

[Read More]

Posted at 01:58PM Apr 07, 2011 by Carsten in Operating Systems  |  Comments[3]

Fixing the IPv6 Firewall on MacOS X 10.6

On MacOS X 10.6 (Snow Leopard), the IPv6 firewall command line utility 'ip6fw' is broken. It does not store filter rules for ICMPv6 types above type 127:

# sudo ip6fw add 20020 allow ipv6-icmp from any to any in icmptype 1,2,3,4,128,129
20020 allow ipv6-icmp from any to any in icmptype 1,2,3,4

Here is the fix...[Read More]

Posted at 06:06PM Apr 03, 2011 by Carsten in Operating Systems  |  Comments[0]

DNS information in IPv6 Router Advertisement on MacOS X

Pierre Ynard, the developer of 'rdnssd', was able to fix the issue with the 'ppoll' interface on MacOS X (see Debugging a shortlived MacOS application). The fix is now in the SVN code and will be available in the next release of 'rdnssd'.

It is now possible to distribute DNS server information to IPv6 clients via router advertisement messages.[Read More]

Posted at 04:48PM Mar 26, 2011 by Carsten in Operating Systems  |  Comments[0]

Debugging a shortlived MacOS application

Yesterday I had to debug a MacOS X commandline program that segfaulted immediatly after starting. This program is 'rdnssd' (Recursive DNS Servers discovery Daemon, http://rdnssd.linkfanel.net/). 'rdnssd' implements the client part of RFC 5006 - IPv6 Router Advertisement Option for DNS Configuration. This function lets an IPv6 router send out DNS server IP address information as part of the Router Advertisment messages, helping client finding a DNS server without the need of DHCP or local configuration.[Read More]

Posted at 06:56PM Mar 10, 2011 by Carsten in Operating Systems  |  Comments[0]

'Timemachine'ish backup with ZFS and rsync

Apple MacOS X Timemachine is a nice piece of software. However it does not compress the data, and it only works on MacOS X. I was looking to a similar solution that works also on other Unix Systems (as well as MacOS X) and does transparent compression of the data. The idea is to have multiple backups on one disk, each backup showing the state of the source hard disk or directory at the time of the backup, browsable by the normal file system tools, without storing any data duplicated. I found a solution using the ZFS file system and 'rsync' (rsync is pre-installed on most Unixish operating systems).

Requirements

• MacOS X 10.5 with ZFS R/W (ZFS on MacOS-Forge), Linux with ZFS-FUSE, FreeBSD with ZFS or Solaris/OpenSolaris
• rsync
• external backup hard drive (USB, FireWire, ...)

Step 1: preparing a ZFS file system

writing a GPT label on the external disk (be sure to not format your 'main' disk here!):

createing a ZFS pool on the disk called 'macbook-backup':

enable compression on the new pool and disable ATIME:

the hard drive is now prepared.

Step 2: creating the first (the 'base') backup

next I copy all files from my backup-source directory (or the whole source disk) to the backup:

depending on the size of the data to backup, this will take a while.

Once the backup is finished, we can access all files under '/Volumes/macbook-backup/base'. With the ZFS command I can check the compression-ratio of our backup:

Step 3: creating an incremental backup

The directory for my new, incremental backup will be '/Volumes/macbook-backup/20080804'. So far the new file system does not use any space on the hard drive. Now I do the new backup with 'rsync':

The new backup will only take as much new space on the backup hard drive as there were changes compared to the base backup. But still I am able to browse through the file system at '/Volumes/macbook-backup/20080804' and see all files that were available at the date of the 2nd backup.

Any subsequent snapshots for more backups will be done from the 20080804 file system.

Posted at 03:24PM Aug 05, 2008 by Carsten in Operating Systems  |  Comments[0]