Date: Mon, 25 Apr 2005 07:56:16 +1000 From: Matthew Sullivan <matthew@uq.edu.au> To: Andre Oppermann <andre@freebsd.org> Cc: freebsd-current@freebsd.org Subject: Re: DF (Don't frag) issues Message-ID: <426C1600.106@uq.edu.au> In-Reply-To: <426BC78A.3E56D99B@freebsd.org> References: <426426AE.2060406@uq.edu.au> <20050420084413.GA27304@walton.maths.tcd.ie> <42663EA1.3020409@uq.edu.au> <426A3F49.6090203@uq.edu.au> <20050424150211.GA87520@walton.maths.tcd.ie> <426BC78A.3E56D99B@freebsd.org>
next in thread | previous in thread | raw e-mail | index | archive | help
This is a cryptographically signed message in MIME format. --------------ms070602060505020301080106 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Andre Oppermann wrote: >David Malone wrote: > > >>On Sat, Apr 23, 2005 at 10:27:53PM +1000, Matthew Sullivan wrote: >> >> >>>Ok well thanks to Andrew @ Supernews and a lot of debugging it appears >>>there is a bug.... >>> >>>sys/netinet/ip_icmp.c: line 440 >>> if (!mtu) >>> mtu = ip_next_mtu(mtu, 1); >>>Problem is ip_next_mtu will always return 0 when called with (0, 1) ... >>> >>> >>I think this might be a bug, but Andre would know better. Andre - >>it looks to me as if the first argument to ip_next_mtu here should >>be the current MTU for the path, but it is being set to the mtu >>from the ICMP message, which (in this case) is zero. >> >> > >This is a bug indeed. Let me think how to fix this most efficiently... > > > >>(This is in the code that has just been moved to tcp_ctlinput.) >> >> >> >>>Apparently the gateway should be suggesting a MTU value for use.... the >>>gateway is also FreeBSD 5.3 so something needs fixing .. :-/ >>> >>> >>Are you using ip fast forwarding on the gateway? It calculates the >>size that is put into the ICMP message in a slightly different way >>to the other forwrd path. >> >> > >The quoted code above is used only for incoming ICMP packets. It >does not generate them? What is the problem being observed exactly? > > > As David suggested my config is shown here: http://lists.freebsd.org/pipermail/freebsd-current/2005-April/048980.html After talking with people I see 2 issues..... 1/ The bug is being triggered when the incoming 'need frag' ICMP message doesn't have a suggested value. This ICMP message is being generated by 'stealth.sorbs.net' which is a FreeBSD 5.3 p9 server running FAST_IPSEC (no crypto card yet - waiting for delivery), and otherwise pretty standard kernel. As for fast forwarding: net.inet.ip.fastforwarding: 0 2/ The bug itself is also a problem, as it cannot be guarenteed that the host returning the ICMP 'need frag' will fill in a suggested mtu, so that also needs to be looked at (but I guess you know that already ;-)) Regards, Mat -- Matthew Sullivan Specialist Systems Programmer Information Technology Services The University of Queensland --------------ms070602060505020301080106 Content-Type: application/x-pkcs7-signature; name="smime.p7s" Content-Transfer-Encoding: base64 Content-Disposition: attachment; filename="smime.p7s" Content-Description: S/MIME Cryptographic Signature MIAGCSqGSIb3DQEHAqCAMIACAQExCzAJBgUrDgMCGgUAMIAGCSqGSIb3DQEHAQAAoIIG7DCC A3IwggJaoAMCAQICASowDQYJKoZIhvcNAQEEBQAwgaMxCzAJBgNVBAYTAkFVMRMwEQYDVQQI EwpRdWVlbnNsYW5kMREwDwYDVQQHEwhCcmlzYmFuZTElMCMGA1UEChMcVGhlIFVuaXZlcnNp dHkgb2YgUXVlZW5zbGFuZDEoMCYGA1UECxMfSW5mb3JtYXRpb24gVGVjaG5vbG9neSBTZXJ2 aWNlczEbMBkGA1UEAxMSQ2VydGlmaWNhdGUgU2VydmVyMB4XDTA0MDEyMTIzMzYyMVoXDTA2 MDEyMTIzMzYyMVowgbIxCzAJBgNVBAYTAkFVMSUwIwYDVQQKExxUaGUgVW5pdmVyc2l0eSBv ZiBRdWVlbnNsYW5kMScwJQYDVQQLEx5JbmZvcm1hdGlvbiBUZWNub2xvZ3kgU2VydmljZXMx FjAUBgoJkiaJk/IsZAEBEwZjY21hdHQxGTAXBgNVBAMTEE1hdHRoZXcgU3VsbGl2YW4xIDAe BgkqhkiG9w0BCQEWEW1hdHRoZXdAdXEuZWR1LmF1MFwwDQYJKoZIhvcNAQEBBQADSwAwSAJB AJsUfrw/QUqKIzDverWc2F4GFFRZmIeO+bAl+7BM6x/9frMzOtygx4QGb4oQwtOE8Sda1aIs v+yJF3Di9EuUyvMCAwEAAaNoMGYwDgYDVR0PAQH/BAQDAgXgMBEGCWCGSAGG+EIBAQQEAwIF oDAfBgNVHSMEGDAWgBQmqtoyueiWTYZBinvsnzeOWLtUuzAgBgNVHREEGTAXgRVtYXR0aGV3 QGl0cy51cS5lZHUuYXUwDQYJKoZIhvcNAQEEBQADggEBAF2gZrkqZsZlHd4K/+yBN6qrpD61 hctDf7/Eg4jk6DMknEs6nvHMFUMZ4SXvkqPLnHBygTARKAs7qBSLd7mUUBOOQEgk6ovQVY6S 1CDSt3P9O6wjG0K1igtk8v6u7lkQ8p2STXqrOePVINdaucUgBO/IpeUtt9ATl1qvPTWyM/fz oUZsIKeYjNQVEQsuimrZjdbIAFxdl1fggSngUv64wBn8wCssGrPZIZA2lpBBEW1wejoWrDOH IIr+SspGd0i8MovDTMRSvgTERLki17FU/ANilcrSXiODKeIvpXhnQqVScnsoMSZmBmN2QIoG SnBjNK5mYxx5E3v20VOwtP1hVdEwggNyMIICWqADAgECAgEqMA0GCSqGSIb3DQEBBAUAMIGj MQswCQYDVQQGEwJBVTETMBEGA1UECBMKUXVlZW5zbGFuZDERMA8GA1UEBxMIQnJpc2JhbmUx JTAjBgNVBAoTHFRoZSBVbml2ZXJzaXR5IG9mIFF1ZWVuc2xhbmQxKDAmBgNVBAsTH0luZm9y bWF0aW9uIFRlY2hub2xvZ3kgU2VydmljZXMxGzAZBgNVBAMTEkNlcnRpZmljYXRlIFNlcnZl cjAeFw0wNDAxMjEyMzM2MjFaFw0wNjAxMjEyMzM2MjFaMIGyMQswCQYDVQQGEwJBVTElMCMG A1UEChMcVGhlIFVuaXZlcnNpdHkgb2YgUXVlZW5zbGFuZDEnMCUGA1UECxMeSW5mb3JtYXRp b24gVGVjbm9sb2d5IFNlcnZpY2VzMRYwFAYKCZImiZPyLGQBARMGY2NtYXR0MRkwFwYDVQQD ExBNYXR0aGV3IFN1bGxpdmFuMSAwHgYJKoZIhvcNAQkBFhFtYXR0aGV3QHVxLmVkdS5hdTBc MA0GCSqGSIb3DQEBAQUAA0sAMEgCQQCbFH68P0FKiiMw73q1nNheBhRUWZiHjvmwJfuwTOsf /X6zMzrcoMeEBm+KEMLThPEnWtWiLL/siRdw4vRLlMrzAgMBAAGjaDBmMA4GA1UdDwEB/wQE AwIF4DARBglghkgBhvhCAQEEBAMCBaAwHwYDVR0jBBgwFoAUJqraMrnolk2GQYp77J83jli7 VLswIAYDVR0RBBkwF4EVbWF0dGhld0BpdHMudXEuZWR1LmF1MA0GCSqGSIb3DQEBBAUAA4IB AQBdoGa5KmbGZR3eCv/sgTeqq6Q+tYXLQ3+/xIOI5OgzJJxLOp7xzBVDGeEl75Kjy5xwcoEw ESgLO6gUi3e5lFATjkBIJOqL0FWOktQg0rdz/TusIxtCtYoLZPL+ru5ZEPKdkk16qznj1SDX WrnFIATvyKXlLbfQE5darz01sjP386FGbCCnmIzUFRELLopq2Y3WyABcXZdX4IEp4FL+uMAZ /MArLBqz2SGQNpaQQRFtcHo6FqwzhyCK/krKRndIvDKLw0zEUr4ExES5ItexVPwDYpXK0l4j gyniL6V4Z0KlUnJ7KDEmZgZjdkCKBkpwYzSuZmMceRN79tFTsLT9YVXRMYIDQDCCAzwCAQEw gakwgaMxCzAJBgNVBAYTAkFVMRMwEQYDVQQIEwpRdWVlbnNsYW5kMREwDwYDVQQHEwhCcmlz YmFuZTElMCMGA1UEChMcVGhlIFVuaXZlcnNpdHkgb2YgUXVlZW5zbGFuZDEoMCYGA1UECxMf SW5mb3JtYXRpb24gVGVjaG5vbG9neSBTZXJ2aWNlczEbMBkGA1UEAxMSQ2VydGlmaWNhdGUg U2VydmVyAgEqMAkGBSsOAwIaBQCgggItMBgGCSqGSIb3DQEJAzELBgkqhkiG9w0BBwEwHAYJ KoZIhvcNAQkFMQ8XDTA1MDQyNDIxNTYxNlowIwYJKoZIhvcNAQkEMRYEFDILw9fzIocfjjaS as/6eFz8tul3MFIGCSqGSIb3DQEJDzFFMEMwCgYIKoZIhvcNAwcwDgYIKoZIhvcNAwICAgCA MA0GCCqGSIb3DQMCAgFAMAcGBSsOAwIHMA0GCCqGSIb3DQMCAgEoMIG6BgkrBgEEAYI3EAQx gawwgakwgaMxCzAJBgNVBAYTAkFVMRMwEQYDVQQIEwpRdWVlbnNsYW5kMREwDwYDVQQHEwhC cmlzYmFuZTElMCMGA1UEChMcVGhlIFVuaXZlcnNpdHkgb2YgUXVlZW5zbGFuZDEoMCYGA1UE CxMfSW5mb3JtYXRpb24gVGVjaG5vbG9neSBTZXJ2aWNlczEbMBkGA1UEAxMSQ2VydGlmaWNh dGUgU2VydmVyAgEqMIG8BgsqhkiG9w0BCRACCzGBrKCBqTCBozELMAkGA1UEBhMCQVUxEzAR BgNVBAgTClF1ZWVuc2xhbmQxETAPBgNVBAcTCEJyaXNiYW5lMSUwIwYDVQQKExxUaGUgVW5p dmVyc2l0eSBvZiBRdWVlbnNsYW5kMSgwJgYDVQQLEx9JbmZvcm1hdGlvbiBUZWNobm9sb2d5 IFNlcnZpY2VzMRswGQYDVQQDExJDZXJ0aWZpY2F0ZSBTZXJ2ZXICASowDQYJKoZIhvcNAQEB BQAEQGuE+aAd3Sd023A6/iyjQSAInMzIyd+GLX9QeVuyyLaGQSB8N1R+BVfozMokG/hm+fjf UD7hVKHAebtE/Bwl724AAAAAAAA= --------------ms070602060505020301080106--
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?426C1600.106>