Wednesday, June 30, 2010

Sendmail and broken DNS

An ISP I use recently switched DNS servers and this, it turns out, broke sendmail.  Running
echo 'check_mail' | sdmail -d8.20 -bt
dns_getcanonname(, trymx=1)
dns_getcanonname: trying (AAAA)
        NO: errno=0, h_errno=1
dns_getcanonname: trying (AAAA)
        NO: errno=0, h_errno=1
which is not good.  Adding
O ResolverOptions=WorkAroundBrokenAAAA
to fixed things
dns_getcanonname(, trymx=1)
dns_getcanonname: trying (AAAA)
        NO: errno=0, h_errno=4
dns_getcanonname: trying (A)
The sendmail change notes say
New ResolverOptions setting: WorkAroundBrokenAAAA.  When
attempting to canonify a hostname, some broken nameservers
will return SERVFAIL (a temporary failure) on T_AAAA (IPv6)
lookups.  If you want to excuse this behavior, use this new 
flag.  Suggested by Chris Foote of SE Network Access and 
Mark Roth of the University of Illinois at
which means someone will have to fix the DNS server...

Macbook noisy USB

I have a nice little Total Bithead from Headroom (, whom by and large know what they're talking about.  The Total Bithead works great on computers other than my Macbook where there is a constant hiss (not a ground loop hum).  I hear this is a fairly well known issue with Mac laptops.  Sigh...

Monday, June 21, 2010

OS X, X11, and modifier keys

I had the strangest thing happen recently: when I fired up X11 in OS X (including wireshark, nomachine, etc.) and none of the modifier keys (control, and even shift!) would work.  I poked around and found that System Preferences, Language & Text, Input Sources, had a direct effect.  I had recently turned on Unicode Hex Input -- if one fires X11 up with this as the input source, the modifier keys won't work.  Choosing "US" solved the problem...  Hope this helps someone from beating their head against the monitor.