Steve’s Software Trek

I was invited to attend Sharkfest ‘08, a conference for Wireshark users and developers, held March 31-April 2 at Foothill College in Los Altos Hills, California. I had a great time, and am so grateful that Gerald invited me to attend. I attended as a Wireshark developer since I actively maintain the BACnet dissector. I went to the conference with several goals in mind:

1. Figure out how to do BACnet segmentation
2. Figure out how to get BACnet MS/TP into libpcap/winpcap.
3. Add a couple of BACnet dissector enhancements to Wireshark.
4. Learn about using Wireshark for problem network analysis.

I attended Laura Chappell’s training sessions, and learned a whole lot about Network analysis and the love-hate relationship between TCP/IP SYN, ACK, and Keepalives (#4 completed). I also wrote some Wireshark code during the classes which I promply submitted (#3 completed). Loris came into the activity center and sat down with my son Joshua and me, and so we discussed how to integrate BACnet MS/TP RS485 from serial port into libpcap/winpcap (#2 completed). On the last day and the last session of the conference, I attended a session by Richard Sharpe about file sharing protocols and learned about Wireshark conversations (#1 completed).

We were treated to an inspiration talk on Tuesday morning by Vint Cerf. After the talk, I went to Laura’s session, and Joshua talked to Vint. Vint signed Joshua’s Half-Life player guide, had photos taken with Vint and Gerald, and the Wireshark crew gave Joshua some swag.

Gerald treated the developers to dinner on Tuesday night at Trader Vic’s. I drove to dinner with Joshua and Jaap Keuter, and learned about PBX systems and Jaap’s passion for skydiving. At dinner I sat next to Ulf Lamping and learned about yet another division of Siemens and about Ulf’s love for motorcycle riding. Guy Harrris and Mike sat across from me.  Joshua ate with Gerald’s wife and daughter, and John Bruno’s wife.

The Foothill College campus was beautiful and on Spring Break. The food was awesome and plentiful.  The people were great!  The Wireshark sessions were helpful.  Maybe I will get to attend next year.

I helped create an Autism support group website several months ago. I needed some Autism related clipart and tried to find some of the colorful jigsaw puzzle pieces that are often found on Autism related sites and accessories. I didn’t find any that were suitable or in the public domain and decided to create my own. I found a single puzzle piece on the OpenClipart website. The OpenClipart website has lots of public domain clipart in SVG format.

Using Inkscape, a free and open source graphics illustration application, I fit four single puzzle pieces together and colored them. Then I fit those four pieces together until I had a small mat of puzzle pieces. I tried to match the color scheme with an Autism ribbon that I had seen. I exported the small mat into PNG format. I used the GIMP, a free and open source image manipulation tool, to add several of these together. I ended up with an autism puzzle background that I could create shapes or words in using the GIMP and masks.

I never did use the words on the website. I did use the small four puzzle piece on the website. The Autism puzzle piece also seems to be a popular search term for that site.

I was minding my own business, coding the BACnet stack project, and decided to commit some files to subversion on SourceForge. However, tortoise-svn gave me the “inconsistent newlines” error. I googled the problem, and found a solution, but that solution didn’t fix the problem - it only masked the problem since my files were legitimate C files.

I fired up SciTE with the problem file, and selected Options - Convert Line End Characters. After saving the changes, I promptly committed the problem file to subversion without having to change thesvn:eol-style option for that file. Problem solved!

I run a couple of servers at my house. One of them is my fileserver, and it uses Samba to do simple Windows filesharing. My 20 GB digital photos partition was full, so I got a 120 GB harddrive and setup an Ubuntu Server 6.06 based fileserver. I transferred the files using rsync, and installed samba on the new server. I set the UID=nobody and the GID=users on all the files. I set the group id inheritance bit on the Linux directories, and removed the world/other rights.

#!/bin/bash
# files are read/write for group and owner
find $1 -type f -exec chmod 660 {} \;
# directories are read/write/cd-able/inherited GID
find $1 -type d -exec chmod 02770 {} \;
# make these files owner=nobody, group=users
chown -R nobody:users $1

I setup Samba to mimic the Linux file system, and forced some settings when new files and directories are created. Here is my smb.conf entry:

[data]
comment = Common Data Directory
path = /home/skarg/data
force user = nobody
force group = users
read only = No
create mask = 0660
force create mode = 0660
directory mask = 02770
force directory mode = 02770
inherit permissions = Yes
guest ok = Yes

Normally, you can add a CIFS mount in /etc/fstab, and specify the UID and GID that the linux filesystem will use. But the cifs filesystem mount wasn’t using the UID that I specified, and that’s when I discovered that Samba now has unix extensions, which cause the problem that I was seeing. Unix extensions can be turned off in samba by adding the following line to /etc/samba/smb.conf:

[global]
unix extensions = no
I also turned off the extensions on the workstation:

echo 0 > /proc/fs/cifs/LinuxExtensionsEnabled

I was trying to get one of the other Ubuntu Server based linux servers to mount the Windows share, but kept getting an error message:

CIFS VFS: cifs_mount failed w/return code = -22