problem with DNS lookups on non-IPv4-only-mode?

Darren Tucker dtucker at zip.com.au
Wed Jun 9 14:28:43 EST 2004


Kendell Welch wrote:
> Below are some details about a few of the servers on which I encountered
> the hanging DNS problem...I'm afraid that the BSD account I had trouble
> with is no longer available...Windows OpenSSH servers have never had the
> problem as best as I can tell.
[..]

Try this test program to see how long various get*info operations take, 
it approximates what sshd will do.  Feed it a list of names equivalent 
to what your clients are looking up, eg:

$ ./a.out www.openssh.com www.openbsd.org openbsd.org www.ibm.com
www.openssh.com:1383 getaddrinfo(0.458s) getnameinfo(0.000s)
www.openbsd.org:966 getaddrinfo(0.502s) getnameinfo(0.000s)
openbsd.org:2153 getaddrinfo(0.181s) getnameinfo(0.000s)
www.ibm.com:2163 getaddrinfo(0.423s) getnameinfo(0.000s) 
getnameinfo(0.000s) getnameinfo(0.000s) getnameinfo(0.000s) 
getnameinfo(0.000s) getnameinfo(0.000s)

Also try with and without nscd running on your hosts.

-- 
Darren Tucker (dtucker at zip.com.au)
GPG key 8FF4FA69 / D9A3 86E9 7EEE AF4B B2D4  37C9 C982 80C7 8FF4 FA69
     Good judgement comes with experience. Unfortunately, the experience
usually comes from bad judgement.
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