I also ordered a new network laser printer, and actually not an HP! It’s a Samsung ML-2851NDR. The OpenPrinting database says that the very similar model Samsung-ML-2851ND works perfectly so I hope that the “R” does not mean “Requires Microsoft Windows”. It was cheaper than the HP LaserJet P1505N, even though the Samsung has duplex support and the HP does not.  Hopefully I will not share the experiences in this negative Samsung ML-2851NDR review.

At least I have the tools in Ubuntu to debug this issue. This is a simplified version and approximate order of what I did.

First, create ~/.gdbinit to make GDB a tad more user-friendly:

set pagination off
set radix 16
set print pretty
set history save on

Second, add ddebs.ubuntu.com to /etc/apt/sources.list:

deb http://ddebs.ubuntu.com/ jaunty main restricted universe multiverse
deb http://ddebs.ubuntu.com/ jaunty-updates main restricted universe multiverse
deb http://ddebs.ubuntu.com/ jaunty-security main restricted universe multiverse
deb http://ddebs.ubuntu.com/ jaunty-proposed main restricted universe multiverse

Install some debug symbols:

sudo apt-get install firefox-3.0-dbgsym libnspr4-0d-dbgsym xulrunner-1.9-dbgsym

Debugging time!

$ gdb `which firefox` `pidof firefox`
…
(gdb) thread apply all bt
…
Thread 2 (Thread 0xb08eab90 (LWP 4253)):
…
#9  0xb7e16c7f in getaddrinfo () from /lib/tls/i686/cmov/libc.so.6
#10 0xb7c8d739 in PR_GetAddrInfoByName (hostname=0xbc01ff4 “safebrowsing-cache.google.com”, af=0×0, flags=0×8020) at prnetdb.c:2026
#11 0xb7267940 in nsHostResolver::ThreadFunc (arg=0×92d9fd8) at nsHostResolver.cpp:697
…

Thread 1 (Thread 0xb7d4b6d0 (LWP 4243)):
#0  0xb8003422 in __kernel_vsyscall ()
#1  0xb7fe30e5 in pthread_cond_wait@@GLIBC_2.3.2 () from /lib/tls/i686/cmov/libpthread.so.0
#2  0xb7c94ed9 in PR_WaitCondVar (cvar=0xcd1ebf8, timeout=0xffffffff) at ptsynch.c:405
#3  0xb7c94f57 in PR_Wait (mon=0xd47d178, timeout=0xffffffff) at ptsynch.c:584
#4  0xb726621b in nsDNSService::Resolve (this=0×92d4b00, hostname=@0xabaf730, flags=<value optimized out>, result=0xbff19ac0) at nsDNSService2.cpp:49

So, we have a thread that is resolving “safebrowsing-cache.google.com” and another thread waiting for this hostname to be resolved. Could this be an issue?

Back at the command line, is there an issue with this domain name? Checking on my local computer:

$ host safebrowsing-cache.google.com
;; connection timed out; no servers could be reached

Trouble at Google? I must confirm that, so I login to one of my servers and run the same command:

$ host safebrowsing-cache.google.com
;; Truncated, retrying in TCP mode.
safebrowsing-cache.google.com is an alias for safebrowsing.cache.l.google.com.
safebrowsing.cache.l.google.com has address 74.125.10.92
…

Works fine, but what does Truncated, retrying in TCP mode mean? I will investigate that later.

Apparently the company firewall is unable to resolve this domain name, at least for the time being. Google Safe Browsing is built into Firefox 3, so how do I disable it? I looked in about:config and yes, there was a setting called browser.safebrowsing.enabled set to true. I set it to false and… Firefox still froze. Looking at about:config again, I found browser.safebrowsing.malware.enabled and set that one to false as well. Now I am able to write this blog post!

Disabling these configuration options is only curing the symptoms, not the disease. But can I cure an enterprise DNS server that fails to handle truncated responses? I doubt it.

This computer is currently using the AMD ‘fglrx’ graphics driver. No version of this driver is available that works with your hardware in Ubuntu 9.04.

My graphics card (three years old by now) is described by lspci as an ATI Technologies Inc M56GL [Mobility FireGL V5200] and apparently these are no longer supported by the properitary fglrx driver. The Open Source radeon driver is rumoured to be pretty good these days but “never change something that works” is pretty useful on laptop where for example Suspend should work.

Speaking of the graphics card, dual-head with my LG L1510SF touch screen monitor works, but the touch stuff needs some tweaking and I’ll get back to that in another blog post.

# of entries in the database         : 16077
# of one hit entries in the database : 15100
Oldest entry in database             : 65 days ago

This means that almost 94% of the attempts to send mail through my server are only made once!

Unfortunately Facebook and Google Mail do not play well with greylisting, as attempts that are told Service temporarily unavailable, please try later by greylisting are very likely to be retried from a different IP. I’ve made a little script that scans /var/log/mail.log for such mail servers and add them to the gld whitelist table.

The main issue with the upgrade was problems with verifying the hash of both package lists and packages. Some apt bug probably, but I don’t prioritize further investigation right now…

I checked the mail log from time to time to see that things were working properly, and after a while I noticed that a number of SMTP servers were refusing mail to me. My server had been listed in The Spamhaus Exploits Block List (XBL) for some reason! Why?

My server was actually listed in the Composite Blocking List (CBL), and it was listed because it sent a bad  HELO in its SMTP conversation. After a minor wild goose chase I realized that I simply had forgotten to change myhostname in /etc/postfix/main.cf from the default! I corrected the hostname setting in postfix, verified that HELO  was correct, requested unlisting from CBL and things worked fine the next day.

Yesterday I noticed a problem with ssh on the Dell Inspiron 1525: I could ssh in any direction between the laptop and other computers on the same wireless network, but not to a computer outside of the wireless network. The issue was already reported as Bug #237894: I cannot connect to any server. Conection hangs up at "channel 0: open confirm rwindow 0 rmax 32768". The solution – as documented in the comments to the bug report – is easy but a bit unexpected: Disable the wl driver and use ndiswrapper for the wireless network interface! As I already had ndiswrapper working in Ubuntu 7.10, i only had to reboot after disabling the wl driver and the ndiswrapper was used instead and ssh worked!

Update Photos and comments from BestBrains.

My wife upgraded the Dell Inspiron 1525 to Ubuntu 8.04 ("Hardy Heron") the other day and as far as I know, everything works fine after correcting the No Sound After Distribution Upgrade issue. I still haven’t upgraded my Thinkpad T60p from Ubuntu 7.10 and it makes be both proud and a bit annoyed that she’s running a more recent Ubuntu release!

Update Continued on Highway to Dell, part six.