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| -rw-r--r-- | chapter_16.xml | 127 |
1 files changed, 81 insertions, 46 deletions
diff --git a/chapter_16.xml b/chapter_16.xml index b8872f2..c95e57a 100644 --- a/chapter_16.xml +++ b/chapter_16.xml @@ -84,26 +84,16 @@ packets 2 10.0.0.1 (10.0.0.1) 7.642 ms 8.019 ms 6.006 ms 3 68.1.8.49 (68.1.8.49) 10.446 ms 9.739 ms 7.003 ms 4 68.1.8.69 (68.1.8.69) 11.564 ms 6.235 ms 7.971 ms - 5 dalsbbrj01-ae0.r2.dl.cox.net (68.1.0.142) 43.859 ms 43.287 ms -44.125 ms - 6 dpr1-ge-2-0-0.dallasequinix.savvis.net (204.70.204.146) 41.927 ms -58.247 ms 44.989 ms - 7 cr2-tengige0-7-5-0.dallas.savvis.net (204.70.196.29) 42.577 ms -46.110 ms 43.977 ms - 8 cr1-pos-0-3-3-0.losangeles.savvis.net (204.70.194.53) 78.070 ms -76.735 ms 76.145 ms - 9 bpr1-ge-3-0-0.LosAngeles.savvis.net (204.70.192.222) 77.533 ms -108.328 ms 120.096 ms -10 wiltel-communications-group-inc.LosAngeles.savvis.net -(208.173.55.186) 79.607 ms 76.847 ms 75.998 ms -11 tg9-4.cr01.lsancarc.integra.net (209.63.113.57) 84.789 ms 85.436 -ms 85.575 ms -12 tg13-1.cr01.sntdcabl.integra.net (209.63.113.106) 87.608 ms -84.278 ms 86.922 ms -13 tg13-4.cr02.sntdcabl.integra.net (209.63.113.134) 87.284 ms -85.924 ms 86.102 ms -14 tg13-1.cr02.rcrdcauu.integra.net (209.63.114.169) 85.578 ms -85.285 ms 84.148 ms + 5 dalsbbrj01-ae0.r2.dl.cox.net (68.1.0.142) 43.859 ms 43.287 ms 44.125 ms + 6 dpr1-ge-2-0-0.dallasequinix.savvis.net (204.70.204.146) 41.927 ms 58.247 ms 44.989 ms + 7 cr2-tengige0-7-5-0.dallas.savvis.net (204.70.196.29) 42.577 ms 46.110 ms 43.977 ms + 8 cr1-pos-0-3-3-0.losangeles.savvis.net (204.70.194.53) 78.070 ms 76.735 ms 76.145 ms + 9 bpr1-ge-3-0-0.LosAngeles.savvis.net (204.70.192.222) 77.533 ms 108.328 ms 120.096 ms +10 wiltel-communications-group-inc.LosAngeles.savvis.net (208.173.55.186) 79.607 ms 76.847 ms 75.998 ms +11 tg9-4.cr01.lsancarc.integra.net (209.63.113.57) 84.789 ms 85.436 ms 85.575 ms +12 tg13-1.cr01.sntdcabl.integra.net (209.63.113.106) 87.608 ms 84.278 ms 86.922 ms +13 tg13-4.cr02.sntdcabl.integra.net (209.63.113.134) 87.284 ms 85.924 ms 86.102 ms +14 tg13-1.cr02.rcrdcauu.integra.net (209.63.114.169) 85.578 ms 85.285 ms 84.148 ms 15 209.63.99.166 (209.63.99.166) 84.515 ms 85.424 ms 85.956 ms 16 208.186.199.158 (208.186.199.158) 86.557 ms 85.822 ms 86.072 ms 17 sac-main.cwo.com (209.210.78.20) 88.105 ms 87.467 ms 87.526 ms @@ -290,6 +280,77 @@ general purpose Internet scanners. </section> +<section> +<title>host</title> + +<para> +Often network problems stem from a failure of DNS (Domain Name Service) +which maps domain names to IP addresses. An easy way to perform quick +DNS lookups is the <application>host</application>(1) command. When +this is run, your computer will perform a few common DNS lookups and +return the results. +</para> + +<screen><prompt>darkstar:~# </prompt><userinput>host www.slackware.com</userinput> +www.slackware.com is an alias for slackware.com. +slackware.com has address 64.57.102.34 +slackware.com mail is handled by 1 mail-mx.cwo.com. +</screen> + +</section> + +<section> +<title>dig</title> + +<para> +More complex DNS lookups can be manually performed with the +<application>dig</application>(1) tool. <application>dig</application> +is "the meanest dog in the pound" when it comes to troubleshooting DNS +issues. With this tool, you can perform virtually any DNS lookup from +reverse lookups to A, CNAME, MX, SP, TXT records and more. There are +far too many command-line options and lookup types to go into depth +here, but the man page lists all the common use cases. +</para> + +<screen><prompt>darkstar:~# </prompt><userinput>dig @207.69.188.185 www.slackware.com a</userinput> + +; <<>> DiG 9.4.3-P4 <<>> @207.69.188.185 www.slackware.com a +; (1 server found) +;; global options: printcmd +;; Got answer: +;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 57965 +;; flags: qr rd ra; QUERY: 1, ANSWER: 2, AUTHORITY: 2, ADDITIONAL: 0 + +;; QUESTION SECTION: +;www.slackware.com. IN A + +;; ANSWER SECTION: +www.slackware.com. 86400 IN CNAME slackware.com. +slackware.com. 86400 IN A 64.57.102.34 + +;; AUTHORITY SECTION: +slackware.com. 86400 IN NS ns2.cwo.com. +slackware.com. 86400 IN NS ns1.cwo.com. + +;; Query time: 348 msec +;; SERVER: 207.69.188.185#53(207.69.188.185) +;; WHEN: Sat Jul 3 16:25:10 2010 +;; MSG SIZE rcvd: 105 + +</screen> + +<para> +Let's take a took at the command-line options used above. The +<arg>@207.69.188.185</arg> argument tells +<application>dig</application> what DNS server to query. If it is not +specified, <application>dig</application> will simply use whatever +servers are listed in <filename>/etc/resolv.conf</filename>. The +<arg>a</arg> argument at the end is the type of DNS record to lookup. +In this case we looked for an "A" record which returned an IPv4 address. +</para> + +</section> + </section> <section><title>Web Browsers</title> @@ -495,32 +556,6 @@ lftp ftp.osuosl.org:/pub/slackware/slackware-current> <userinput>bye</userinput> </section> <section> -<title>NNTP Clients</title> - -<para> -Once upon a time when the Internet was young, before the World Wide Web -was invented and no one had heard of hyperlinks, everyone retrieved -their news and information through a service known as Usenet using the -NNTP protocol. It remains today a useful knowledge base of information -on an incredible variety of subjects, but if you wish to access this -information, you're going to need a proper client. Slackware includes -a number of NNTP clients with both console and graphical interfaces, -but we'll only detail the console tools here. Popular graphical news -readers include <application>knode</application> and -<application>pan</application>. -</para> - -<section><title>tin</title> - -</section> - -<section><title>slrn</title> - -</section> - -</section> - -<section> <title>rsync</title> <para> |