From mboxrd@z Thu Jan 1 00:00:00 1970 From: Michael Tremer To: development@lists.ipfire.org Subject: Re: Path MTU discovery broken / advmss Date: Fri, 28 Aug 2015 19:42:11 +0100 Message-ID: <1440787331.18358.90.camel@ipfire.org> In-Reply-To: MIME-Version: 1.0 Content-Type: multipart/mixed; boundary="===============7923299890846866677==" List-Id: --===============7923299890846866677== Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Hi, let's discuss this on the forums then since Arne already answered there: http://forum.ipfire.org/viewtopic.php?f=27&t=14783 -Michael On Fri, 2015-08-28 at 16:23 +0000, John P Poet wrote: > Hi, > > I hope it is okay if I ask a configuration question here. > > A couple of weeks ago, my internet dropped and I noticed that my DSL > modem was rebooting. When it came back up I had a new public IP and > I could no longer load most web pages. Other than google, the ones > which would load were very slow. I was finally able to get a page to > load which suggested this behaviour could be caused by a MTU problem. > I tried lowering the MTU on one of my machines from 1500 to 1492 > and the problem was solved. > > I then went to all of my various computers and changed the MTU to > 1492, except my iPad. Apple being Apple, does not allow users the > ability to change things like MTU. This means that I can still not > get to most web pages, etc, on my iPad. > > Further searching brought up pages like: > https://blog.cloudflare.com/path-mtu-discovery-in-practice/ > http://rtoodtoo.net/path-mtu-ip-fragmentation-and-mss/ > > Given the info on those pages, I have tried to set advmss on my > router to 1452, 1200, 1024, etc. But no matter what I do, I end up > killing the routing completely. I have tried doing things like: > > # echo 1 > /proc/sys/net/ipv4/tcp_mtu_probing > # echo 1024 > /proc/sys/net/ipv4/tcp_base_mss > or > # ip route change 0.0.0.0/0 dev red0 advmss 1024 > Obviously, those are not the correct way to get ipfire to set mss to > a lower value. I am hoping someone can tell me the correct way to > work around a broken "path MTU discovery" issue. > > Thanks, > > John > --===============7923299890846866677== Content-Type: application/pgp-signature Content-Transfer-Encoding: base64 Content-Disposition: attachment; filename="signature.asc" MIME-Version: 1.0 LS0tLS1CRUdJTiBQR1AgU0lHTkFUVVJFLS0tLS0KVmVyc2lvbjogR251UEcgdjEKCmlRSWNCQUFC Q2dBR0JRSlY0S3VEQUFvSkVJQjU4UDl2a0FrSEo5a1FBS20veU5aT0xHVktWRzlBQ2U5cmRuc0cK WWdrcHJFL0hMMVhjdXV3THluT1Bta1hPc0tFd3U3SnllVTJ6K3lZa1daOWVIbEsvd1V6bklaMWVL TFB4N084MAo2M2t6c2pSRysxZ0xRcFZyc3MwajQ0alppTjlJTW9Cbmt0Ky9BYTg1Mjl1dDE5dUcz ZWpnN3N6K3Fic2VzdUlrCnh4VXA4K1BsQy9yU3Z0V2h5K3JlMTNvZXBWTlg1cXVIQ0Y2RStWZ0RR ZXdNcno0OFcwUXArR1hmeU9uWmtGL0cKL1lXeW9NVncyS1NGU015SFNNcTVLWDNFalNWOXBYaGFx YzRSSWozZFZrNnhoQUFyOGVKamR6Q0N1L1RVdHAvVgpBMU5JV0JPQ05sZFRFQzdibGhjT2R6cld4 bjk4bFVqSUNQeUhhRVNhME93N3FIUzBqRmhxc3pDbDlmMlphRzBuCitvWmlQUVN4MG0vWlZQRjlF anlEdURwaDZmQXVVUEVhMDBaTUc5b1p1WktvSEk4Y29oVm9kZUNrREJ4eUwzN1EKdzNBa1o1ajZt WTNReVp5MUZodDhMUXBiV1psWVhERTlSL2p1SkZ3ZCtSZ1lqRENiVjZ0V1hNS1VtUm1EVHJaNwow cktXYjdnVGFsWWw3Q1NpMjBEeDhtekQ0ajdydkptdUdEYkdkWS9uaXFIWmI3cVJkNTNLRXNQdFFo Mmlneko1Ck80anpWYUlicmJpanpJUjVNQWpDQ29YZWp0RlgxRmtXVURvVUR0Rm5pREdxZDhjZVB3 amJtL1FSUjV4ZDhJSVAKMmJiYmhHbWVRUVoxNUNST1BtNWVaUUV2czc0NG9aS20ra0Y3b0pML25H L212cTdycmdjbHJCbDVSUUFjcE0zWApYTUJ0d3FSWHgwZzBaY25WWm1Nawo9NEZSWAotLS0tLUVO RCBQR1AgU0lHTkFUVVJFLS0tLS0K --===============7923299890846866677==--