{"id":689,"date":"2020-06-15T12:00:00","date_gmt":"2020-06-15T19:00:00","guid":{"rendered":"http:\/\/letsbuildroboticswithshadow8472.com\/?p=689"},"modified":"2020-06-15T02:36:45","modified_gmt":"2020-06-15T09:36:45","slug":"beowulf-cluster-part-5-dhcp-and-nat","status":"publish","type":"post","link":"https:\/\/letsbuildroboticswithshadow8472.com\/index.php\/2020\/06\/15\/beowulf-cluster-part-5-dhcp-and-nat\/","title":{"rendered":"\u201cBeowulf Cluster:\u201d Part 5: DHCP and NAT"},"content":{"rendered":"\n<p class=\"wp-block-paragraph\">Good Morning from my Robotics Lab! This is Shadow_8472, and today, I am getting a head start on this post, so I don&#8217;t yet know where the end point for this segments. Let&#8217;s get started!<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">I hate networking. This router project is really taking a lot to learn. I&#8217;m losing track in my memory about what point I was on when the official break in weeks happened. Right now, I&#8217;m just looking forward to the time when I can say I have a custom router, and setting up the &#8220;Beowulf Cluster&#8221; I originally set out to build &#8211;not that I can really call it that anymore&#8211; should be one more week\u2122 after that.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Once I had the network interfaces set up correctly, DHCP wasn&#8217;t far behind. I had a few semicolons missing after some lines, but that was about it. I plugged my laptop into the my little subnet and the Pi assigned it an IP in the range I had told it to. It just wouldn&#8217;t let me at the Internet at large, even though I haven&#8217;t changed <strong>iptables<\/strong> off its default of accepting everything yet. Of note: I was unable to use the Internet even while still connected wirelessly. Two weeks ago (Was it only that short ago?) I would have just poked around with &#8220;black box reasoning&#8221; before concluding that Ethernet superseded Wi-Fi because it is faster, all other factors being equal.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Further investigation led to believe I should look into NAT (Network Address Translation). It&#8217;s disabled by default, likely because if you need it, you&#8217;ll soon learn about it like I&#8217;m doing now.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">A couple guides later, and I had uncommented a line in a config file to allow IP forwarding, but when I used <strong>modprobe ip_forward<\/strong> to add NAT abilities to the kernel, listing out my <strong>iptables<\/strong> gave a warning about legacy software. <\/p>\n\n\n\n<p class=\"has-text-align-center wp-block-paragraph\">***<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Well, this write up is coming due, so here&#8217;s what I&#8217;ve got.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">I worked with a couple friends on my private Minecraft server &#8211;yes the one I&#8217;ve covered here before&#8211; by the names of doflagie and TheRSC. We didn&#8217;t go messing around with NAT tables, but we did inspect the DHCP configuration files some more.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">At least, that was the plan at first. I accidentally broke an interface by editing the file there. Rebooting cut off my connection. I SSH&#8217;ed in over the other interface and promptly broke that one too. I had to swap around cables to fix those config files, so it was all good.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">With my little review from last week out of the way, I went to weed through the actual DHCP config file. I wasn&#8217;t sure where it was, but before I resorted to finding it again online, I noticed one terminal on my workstation was already in a local DHCP directory when it wasn&#8217;t SSH&#8217;ed into somewhere else.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">As part of my workflow, I hooked BlinkyPie up to the Ethernet subnet. Thanks to the default Raspian settings, eth0 overrode wlan0 as the default network interface, so I didn&#8217;t have to disable or disconnect Wi-Fi. Otherwise, Blinky is standing in for a generic microcomputer on this micronetwork.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">It took several hours, but when I rearranged the DHCP config on the Pi4 to reflect the subnet and not the wider home network, I was able to reach out from Blinky through the Pi4. However, I was only allowed to the gateway, and no farther.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">These results are underwhelming. Each last problem feels like it is comprised of a chain of smaller problems, leading to another such chain. I&#8217;m making progress, but if feels like the goalpost is moving on me.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Final question: How hard should this really be? Sure, there are higher lever programs, but how long should a low-level approach like what I&#8217;m doing take to figure out?<\/p>\n","protected":false},"excerpt":{"rendered":"<p>Good Morning from my Robotics Lab! This is Shadow_8472, and today, I am getting a head start on this post, so I don&#8217;t yet know where the end point for this segments. Let&#8217;s get started! I hate networking. This router project is really taking a lot to learn. I&#8217;m losing track in my memory about &hellip; <\/p>\n<p class=\"link-more\"><a href=\"https:\/\/letsbuildroboticswithshadow8472.com\/index.php\/2020\/06\/15\/beowulf-cluster-part-5-dhcp-and-nat\/\" class=\"more-link\">Continue reading<span class=\"screen-reader-text\"> &#8220;\u201cBeowulf Cluster:\u201d Part 5: DHCP and NAT&#8221;<\/span><\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_bbp_topic_count":0,"_bbp_reply_count":0,"_bbp_total_topic_count":0,"_bbp_total_reply_count":0,"_bbp_voice_count":0,"_bbp_anonymous_reply_count":0,"_bbp_forum_subforum_count":0,"footnotes":""},"categories":[2,14],"tags":[],"class_list":["post-689","post","type-post","status-publish","format-standard","hentry","category-linux","category-networking"],"_links":{"self":[{"href":"https:\/\/letsbuildroboticswithshadow8472.com\/index.php\/wp-json\/wp\/v2\/posts\/689","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/letsbuildroboticswithshadow8472.com\/index.php\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/letsbuildroboticswithshadow8472.com\/index.php\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/letsbuildroboticswithshadow8472.com\/index.php\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/letsbuildroboticswithshadow8472.com\/index.php\/wp-json\/wp\/v2\/comments?post=689"}],"version-history":[{"count":1,"href":"https:\/\/letsbuildroboticswithshadow8472.com\/index.php\/wp-json\/wp\/v2\/posts\/689\/revisions"}],"predecessor-version":[{"id":692,"href":"https:\/\/letsbuildroboticswithshadow8472.com\/index.php\/wp-json\/wp\/v2\/posts\/689\/revisions\/692"}],"wp:attachment":[{"href":"https:\/\/letsbuildroboticswithshadow8472.com\/index.php\/wp-json\/wp\/v2\/media?parent=689"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/letsbuildroboticswithshadow8472.com\/index.php\/wp-json\/wp\/v2\/categories?post=689"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/letsbuildroboticswithshadow8472.com\/index.php\/wp-json\/wp\/v2\/tags?post=689"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}