From owner-freebsd-questions@FreeBSD.ORG Wed Jun 5 12:24:50 2013 Return-Path: Delivered-To: freebsd-questions@freebsd.org Received: from mx1.freebsd.org (mx1.FreeBSD.org [8.8.178.115]) by hub.freebsd.org (Postfix) with ESMTP id C420C4B6 for ; Wed, 5 Jun 2013 12:24:50 +0000 (UTC) (envelope-from feld@feld.me) Received: from out1-smtp.messagingengine.com (out1-smtp.messagingengine.com [66.111.4.25]) by mx1.freebsd.org (Postfix) with ESMTP id 999B9166C for ; Wed, 5 Jun 2013 12:24:50 +0000 (UTC) Received: from compute1.internal (compute1.nyi.mail.srv.osa [10.202.2.41]) by gateway1.nyi.mail.srv.osa (Postfix) with ESMTP id 8F08921029 for ; Wed, 5 Jun 2013 08:24:49 -0400 (EDT) Received: from frontend1.nyi.mail.srv.osa ([10.202.2.160]) by compute1.internal (MEProxy); Wed, 05 Jun 2013 08:24:49 -0400 DKIM-Signature: v=1; a=rsa-sha1; c=relaxed/relaxed; d=feld.me; h= content-type:to:subject:references:date:mime-version :content-transfer-encoding:from:message-id:in-reply-to; s= mesmtp; bh=EQJX9B51i1jmGiYFKTCF0MjfaxY=; b=RbW3TIDHBzABBol9IdaBb OrIEhA5WngvONFeJoUcOd333bdp3f14YpzyQyxTrsRvtt4ugqu3RqLWNiEor3J5s 9GgcKTTvvPM5MWP2DkXql1/5YSajbXAn8wT8uEhzBvBadp3OZtv6Den+GwjgW+Df KUEwbkfEyH2Wsyi44+Pd4U= DKIM-Signature: v=1; a=rsa-sha1; c=relaxed/relaxed; d= messagingengine.com; h=content-type:to:subject:references:date :mime-version:content-transfer-encoding:from:message-id :in-reply-to; s=smtpout; bh=EQJX9B51i1jmGiYFKTCF0MjfaxY=; b=Z6FR k/+Ux8sNGixF8nhgQzbS0xMIqEZ/Xzts3yp3diLGTqHxHhlsfh/RVi6u9M0y7Bdr 3meQJMdxkjx20kcUl3EHIsOfbBl57v0L6rPr16oYFTLCvcMpkLVfGWiVM+m8Iq79 oh+0NgcLFIEVD2LeR6IFN/aNB0GcPZoMKJX3fN0= X-Sasl-enc: WNcOGnqHsWPp9mxv7V5FdI8C8Yppqjdn35mcbjZMTWa5 1370435089 Received: from markf.office.supranet.net (unknown [66.170.8.18]) by mail.messagingengine.com (Postfix) with ESMTPA id 57A86C8014A for ; Wed, 5 Jun 2013 08:24:49 -0400 (EDT) Content-Type: text/plain; charset=us-ascii; format=flowed; delsp=yes To: freebsd-questions@freebsd.org Subject: Re: System Calls that do DNS References: Date: Wed, 05 Jun 2013 07:24:48 -0500 MIME-Version: 1.0 Content-Transfer-Encoding: 7bit From: "Mark Felder" Message-ID: In-Reply-To: User-Agent: Opera Mail/12.15 (FreeBSD) X-BeenThere: freebsd-questions@freebsd.org X-Mailman-Version: 2.1.14 Precedence: list List-Id: User questions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 05 Jun 2013 12:24:50 -0000 On Mon, 03 Jun 2013 21:57:07 -0500, Doug Hardie wrote: > I have an unusual situation. A program is doing a DNS lookup and often > the IP address has no reverse DNS entries. As a result the program > hangs for several timeouts. The call is not being made directly in its > code, but is occurring in a system call. There are no specific calls to > DNS, its something else doing it. I have been trying to track down > which system call is doing it, but without success so far. I have tried > syslog calls around each of the system calls I thought might be the > culprit, but my guessing is not very good. How can I identify the > system call that is calling DNS? If I can find it, I hopefully can find > another way to do whatever it does that does not involve a reverse DNS > lookup. > > The system DNS lookups are handled by libc. Probably somewhere in the code here: http://svnweb.freebsd.org/base/head/lib/libc/nameser/