Public bug reported: [impact]
when talking to upstream nameservers, systemd-resolved limits its advertised max packet size as 512 in its edns0 opt. However, one of the primary benefits of edns0 is to allow using packet sizes larger than 512, which is the pre-edns0 max packet size. this results in systemd-resolved failing to handle responses larger than 512 with udp/edns0, and having to fall back to tcp. This is not optimal (since tcp dns imposes significantly higher overhead) and may even cause failures, if a firewall allows udp dns but blocks tcp dns traffic. [test case] TBD [regression potential] failure to correctly look up dns records, or other problems while performing dns lookups with systemd-resolved [scope] this is needed for all releases this still needs fixing upstream ** Affects: systemd (Ubuntu) Importance: Undecided Status: New ** Affects: systemd (Ubuntu Bionic) Importance: Low Assignee: Dan Streetman (ddstreet) Status: In Progress ** Affects: systemd (Ubuntu Focal) Importance: Low Assignee: Dan Streetman (ddstreet) Status: In Progress ** Affects: systemd (Ubuntu Hirsute) Importance: Low Assignee: Dan Streetman (ddstreet) Status: In Progress ** Affects: systemd (Ubuntu Impish) Importance: Undecided Status: New ** Also affects: systemd (Ubuntu Hirsute) Importance: Undecided Status: New ** Also affects: systemd (Ubuntu Bionic) Importance: Undecided Status: New ** Also affects: systemd (Ubuntu Impish) Importance: Undecided Status: New ** Also affects: systemd (Ubuntu Focal) Importance: Undecided Status: New ** Changed in: systemd (Ubuntu Bionic) Status: New => In Progress ** Changed in: systemd (Ubuntu Focal) Status: New => In Progress ** Changed in: systemd (Ubuntu Hirsute) Status: New => In Progress ** Changed in: systemd (Ubuntu Bionic) Importance: Undecided => Low ** Changed in: systemd (Ubuntu Focal) Importance: Undecided => Low ** Changed in: systemd (Ubuntu Hirsute) Importance: Undecided => Low ** Changed in: systemd (Ubuntu Bionic) Assignee: (unassigned) => Dan Streetman (ddstreet) ** Changed in: systemd (Ubuntu Focal) Assignee: (unassigned) => Dan Streetman (ddstreet) ** Changed in: systemd (Ubuntu Hirsute) Assignee: (unassigned) => Dan Streetman (ddstreet) -- 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/1940715 Title: systemd-resolved restricts edns0 advertised max size to 512 Status in systemd package in Ubuntu: New Status in systemd source package in Bionic: In Progress Status in systemd source package in Focal: In Progress Status in systemd source package in Hirsute: In Progress Status in systemd source package in Impish: New Bug description: [impact] when talking to upstream nameservers, systemd-resolved limits its advertised max packet size as 512 in its edns0 opt. However, one of the primary benefits of edns0 is to allow using packet sizes larger than 512, which is the pre-edns0 max packet size. this results in systemd-resolved failing to handle responses larger than 512 with udp/edns0, and having to fall back to tcp. This is not optimal (since tcp dns imposes significantly higher overhead) and may even cause failures, if a firewall allows udp dns but blocks tcp dns traffic. [test case] TBD [regression potential] failure to correctly look up dns records, or other problems while performing dns lookups with systemd-resolved [scope] this is needed for all releases this still needs fixing upstream To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/systemd/+bug/1940715/+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