> We are reffering to the local stub resolver yes, i understand that, but i'm asking if you are talking about local traffic TO the stub resolver, or traffic FROM the stub resolver to your upstream nameserver.
If you have pcap showing the problem, please attach it. If you're not sure what I'm talking about, then you should do: $ sudo systemctl edit systemd-resolved and in the file editor it opens, add this content: [Service] Environment=SYSTEMD_LOG_LEVEL=debug then save the file and reboot. then try looking up your host again (using the local stub resolver of course). Gather the resolved logs and attach or paste them here. $ journalctl -b -u systemd-resolved --no-pager -- You received this bug notification because you are a member of Ubuntu Touch seeded packages, which is subscribed to systemd in Ubuntu. https://bugs.launchpad.net/bugs/1886128 Title: systemd-resolved does not resolve address due to udp payload size. Status in systemd package in Ubuntu: Incomplete Bug description: Description: Ubuntu 18.04.4 LTS Release: 18.04 systemd-resolve --version systemd 237 +PAM +AUDIT +SELINUX +IMA +APPARMOR +SMACK +SYSVINIT +UTMP +LIBCRYPTSETUP +GCRYPT +GNUTLS +ACL +XZ +LZ4 +SECCOMP +BLKID +ELFUTILS +KMOD -IDN2 +IDN -PCRE2 default-hierarchy=hybrid We met an error: on an attempt to resolve address, the following issue appears: ; <<>> DiG 9.11.3-1ubuntu1.11-Ubuntu <<>> mharder-formrec.cognitiveservices.azure.com ;; global options: +cmd ;; Got answer: ;; ->>HEADER<<- opcode: QUERY, status: SERVFAIL, id: 44096 ;; flags: qr rd ra; QUERY: 1, ANSWER: 0, AUTHORITY: 0, ADDITIONAL: 1 ;; OPT PSEUDOSECTION: ; EDNS: version: 0, flags:; udp: 65494 ;; QUESTION SECTION: ;mharder-formrec.cognitiveservices.azure.com. IN A ;; Query time: 231 msec ;; SERVER: 127.0.0.53#53(127.0.0.53) ;; WHEN: Tue Apr 28 20:47:14 UTC 2020 ;; MSG SIZE rcvd: 72 Let me provide you important notes about the issue: 1) It's not reproducing on Ubuntu 16; 2) Bypassing systemd-resolve - everything works fine; 3) Only the difference between systemd-resolve and END is UDP_PAYLOAD_SIZE Successful query: 1135 16:27:25.964386 10.1.0.4 168.63.129.16 DNS 128 Standard query 0xc2d4 A mharder-formrec.cognitiveservices.azure.com OPT Domain Name System (query) Transaction ID: 0xc2d4 Flags: 0x0120 Standard query 0... .... .... .... = Response: Message is a query .000 0... .... .... = Opcode: Standard query (0) .... ..0. .... .... = Truncated: Message is not truncated .... ...1 .... .... = Recursion desired: Do query recursively .... .... .0.. .... = Z: reserved (0) .... .... ..1. .... = AD bit: Set .... .... ...0 .... = Non-authenticated data: Unacceptable Questions: 1 Answer RRs: 0 Authority RRs: 0 Additional RRs: 1 Queries mharder-formrec.cognitiveservices.azure.com: type A, class IN Additional records <Root>: type OPT Name: <Root> Type: OPT (41) UDP payload size: 4096 Higher bits in extended RCODE: 0x00 EDNS0 version: 0 Z: 0x0000 0... .... .... .... = DO bit: Cannot handle DNSSEC security RRs .000 0000 0000 0000 = Reserved: 0x0000 Data length: 12 Option: COOKIE Unsuccessful query: 1128 16:27:25.713886 10.1.0.4 168.63.129.16 DNS 116 Standard query 0x198d A mharder-formrec.cognitiveservices.azure.com OPT Domain Name System (query) Transaction ID: 0x198d Flags: 0x0100 Standard query 0... .... .... .... = Response: Message is a query .000 0... .... .... = Opcode: Standard query (0) .... ..0. .... .... = Truncated: Message is not truncated .... ...1 .... .... = Recursion desired: Do query recursively .... .... .0.. .... = Z: reserved (0) .... .... ...0 .... = Non-authenticated data: Unacceptable Questions: 1 Answer RRs: 0 Authority RRs: 0 Additional RRs: 1 Queries mharder-formrec.cognitiveservices.azure.com: type A, class IN Additional records <Root>: type OPT Name: <Root> Type: OPT (41) UDP payload size: 512 Higher bits in extended RCODE: 0x00 EDNS0 version: 0 Z: 0x0000 0... .... .... .... = DO bit: Cannot handle DNSSEC security RRs .000 0000 0000 0000 = Reserved: 0x0000 Data length: 0 Notable difference: Success: UDP payload size: 4096 Failure: UDP payload size: 512 And notable differences in the responses: Success: Flags: 0x8180 Standard query response, No error .... ..0. .... .... = Truncated: Message is not truncated Failure: Flags: 0x8380 Standard query response, No error .... ..1. .... .... = Truncated: Message is truncated Interestingly, systemd-resolved is setting the maximum payload size to 512 regardless of whether EDNS0 is configured and regardless of what is sent to it for the payload size. I tried to found a way to change UDP_PAYLOAD_SIZE,but it seems it is only possible to change it only with direct code modifications. To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/systemd/+bug/1886128/+subscriptions -- Mailing list: https://launchpad.net/~touch-packages Post to : touch-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~touch-packages More help : https://help.launchpad.net/ListHelp
