Public bug reported: Hello,
I noticed a problem on one of my dual stacked (IPv4 and IPv6) Trusty Tahr machines running unbound. The problem initially was that i failed running dig +trace against it, where it would hang when looking up the root servers. I could verify the problem using unbound-host: === # unbound-host -f /var/lib/unbound/root.key a.root-servers.net Host a.root-servers.net not found: 2(SERVFAIL). Host a.root-servers.net not found: 2(SERVFAIL). Host a.root-servers.net not found: 2(SERVFAIL). === The most interesting part was that when forcing either IPv4 or IPv6, it worked: === # unbound-host -4 -f /var/lib/unbound/root.key a.root-servers.net a.root-servers.net has address 198.41.0.4 a.root-servers.net has IPv6 address 2001:503:ba3e::2:30 # unbound-host -6 -f /var/lib/unbound/root.key a.root-servers.net a.root-servers.net has address 198.41.0.4 a.root-servers.net has IPv6 address 2001:503:ba3e::2:30 === Looking at the debug-output i noticed several occurences of the following messages: === # unbound-host -d -d -f /var/lib/unbound/root.key a.root-servers.net [...] [1436342178] libunbound[14283:0] debug: request has exceeded the maximum number of sends with 17 [1436342178] libunbound[14283:0] debug: return error response SERVFAIL [...] === Comparing this against the changelog of unbound (https://www.unbound.net/download.html) I noticed 1.5.0 had increased the MAX_SENT_COUNT definition from 16 to 32. Attached is a diff which backports this change, which solved my problem. The most annoying thing about this problem is that I can not recreate it on another host which is both the same Ubuntu version and dual stacked. ** Affects: unbound (Ubuntu) Importance: Undecided Status: New ** Attachment added: "unbound_1.4.22-1ubuntu4.14.04.2.patch" https://bugs.launchpad.net/bugs/1472510/+attachment/4426181/+files/unbound_1.4.22-1ubuntu4.14.04.2.patch -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1472510 Title: Unbound returns SERVFAIL for specific query on specific dual stacked machine To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/unbound/+bug/1472510/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
