Ah Jumbo frames, the Power, the Speed, the pure goodness of MTU=9000 \u00e2\u20ac\u201c well, not so fast if you want a stable SSH experience across the internet.<\/p>\n
Here’s what I found; Debian + Jumbo Frames + AT&T Uverse = intermittent, hangs on terminal and SFTP sessions while remotely connected. Recently, I built a new Debian based (Actually, Linux Mint DE) system for the house that I plan to expose port 22 on for remote shell access. I know, pretty common stuff. During the setup of the OS, I started playing around with the MTU size, figuring like my FreeNAS box I should boost the value up from the base 1500 size. I made the config change, everything worked great – at least while I was on the LAN.<\/p>\n
So the next week comes and I’m working down in Houston \u00e2\u20ac\u201c I fire up an ssh session back to the Debian box, I connect without any problem, but then discover I can’t reliably issue even simple commands like \u00e2\u20ac\u0153ls\u00e2\u20ac\u009d without the session locking up, stalling, or just \u00e2\u20ac\u0153hanging\u00e2\u20ac\u009d there. But since the connection does not drop all together, I start troubleshooting other connection issues. It’s not till I SFTP to the box (also a port 22 action) that I begin to suspect something in the Debian side, rather then my client connectivity. My SFTP session, just like the terminal was able to connect and sustain a connection, but after maybe on directory refresh would \u00e2\u20ac\u0153pause\u00e2\u20ac\u009d or \u00e2\u20ac\u0153hang\u00e2\u20ac\u009d and exhibit the same type of behavior as the command line session.<\/p>\n
Mulling all this over, I did the only logical thing an IT Pro would do…. Roll back my changes, setting the MTU back to the default 1500. And like-a-magic remote ssh traffic is back to normal.\u00c2\u00a0 So friends \u00e2\u20ac\u201c learn from my greedy frame size experience.<\/p>\n","protected":false},"excerpt":{"rendered":"
Ah Jumbo frames, the Power, the Speed, the pure goodness of MTU=9000 \u00e2\u20ac\u201c well, not so fast if you want a stable SSH experience across the internet. Here’s what I found; Debian + Jumbo Frames + AT&T Uverse = intermittent, hangs on terminal and SFTP sessions while remotely connected. Recently, I built a new Debian […]<\/p>\n","protected":false},"author":2,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[8,9],"tags":[39,38,40,27],"class_list":["post-175","post","type-post","status-publish","format-standard","hentry","category-internet-networking","category-linuxunix","tag-frame","tag-jumbo","tag-network","tag-ssh"],"_links":{"self":[{"href":"https:\/\/www.degen.net\/index.php?rest_route=\/wp\/v2\/posts\/175","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.degen.net\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.degen.net\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.degen.net\/index.php?rest_route=\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.degen.net\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=175"}],"version-history":[{"count":1,"href":"https:\/\/www.degen.net\/index.php?rest_route=\/wp\/v2\/posts\/175\/revisions"}],"predecessor-version":[{"id":176,"href":"https:\/\/www.degen.net\/index.php?rest_route=\/wp\/v2\/posts\/175\/revisions\/176"}],"wp:attachment":[{"href":"https:\/\/www.degen.net\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=175"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.degen.net\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=175"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.degen.net\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=175"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}