From: curl-library <[email protected]> On Behalf Of Dan Fandrich via curl-library Sent: Thursday, September 29, 2022 5:09 PM To: libcurl development <[email protected]> Cc: Dan Fandrich <[email protected]> Subject: Re: App fails when rebuilt with newer library, but only when MTU is small
On Thu, Sep 29, 2022 at 09: 58: 58PM +0000, Mark Fanara wrote: >> Some servers have an issue with 100-continue, and I don't recall which version >> of libcurl enabled it by default. You could try disabling it and see what >> ZjQcmQRYFpfptBannerStart This Message Is From an Untrusted Sender You have not previously corresponded with this sender. If you do not trust the sender, click the Report Phish button on the Ribbon bar of this email. ZjQcmQRYFpfptBannerEnd >> When the MTU is larger, the TLS packet sequence continues >This seems unlikely to me to be a curl issue. It sounds more likely to be >something lower in the networking stack that's interfering. Try using Wireshark >to sniff the traffic to see if the short application data packets are getting >through, and if they are, if they're being acked. The problem turned out to be the fact that an upstream device was sending ICMP ‘fragmentation needed’ back to me with a MTU next hop value < 576. My newer OS apparently discarded them because of the next hop value. I was able to change the OS path MTU behavior by setting /proc/sys/net/ipv4/ip_no_pmtu_disc to 1 (echo ‘1’ > /proc/sys/net/ipv4/ip_no_pmtu_disc) per https://www.kernel.org/doc/html/latest/networking/ip-sysctl.html. Dan -- Unsubscribe: https://urldefense.com/v3/__https://lists.haxx.se/listinfo/curl-library__;!!HmYJUS2Zvnm8!fgDMkDbFC8imghMBojOn_WffIB6__cMKyC0dJKwzHaYd5leaMvKWOBLM-2YrGwZ0-K2nAa2S3Uiccr1Z2oLNAPFeVJJ8PCM$ Etiquette: https://urldefense.com/v3/__https://curl.se/mail/etiquette.html__;!!HmYJUS2Zvnm8!fgDMkDbFC8imghMBojOn_WffIB6__cMKyC0dJKwzHaYd5leaMvKWOBLM-2YrGwZ0-K2nAa2S3Uiccr1Z2oLNAPFeeDYLnqA$ Caterpillar: Confidential Green -- Unsubscribe: https://lists.haxx.se/listinfo/curl-library Etiquette: https://curl.se/mail/etiquette.html
