Closed cranderson closed 7 months ago
I ran strace -tt on it and found 226 lines like these. There were 229 unreachable hosts in my test, so it seems that the unreachable hosts (which have no DNS records) are triggering these errors.
13:58:47.667631 recvfrom(5, "{\"error\":\"io.systemd.Resolve.Max"..., 135152, MSG_DONTWAIT, NULL, NULL) = 66
13:58:49.167756 recvfrom(5, "{\"error\":\"io.systemd.Resolve.Max"..., 131080, MSG_DONTWAIT, NULL, NULL) = 66
13:58:50.667649 recvfrom(5, "{\"error\":\"io.systemd.Resolve.Max"..., 131080, MSG_DONTWAIT, NULL, NULL) = 66
13:58:52.167538 recvfrom(5, "{\"error\":\"io.systemd.Resolve.Max"..., 131080, MSG_DONTWAIT, NULL, NULL) = 66
13:58:53.667540 recvfrom(5, "{\"error\":\"io.systemd.Resolve.Max"..., 131080, MSG_DONTWAIT, NULL, NULL) = 66
13:58:55.167634 recvfrom(5, "{\"error\":\"io.systemd.Resolve.Max"..., 131080, MSG_DONTWAIT, NULL, NULL) = 66
13:58:56.667612 recvfrom(5, "{\"error\":\"io.systemd.Resolve.Max"..., 131080, MSG_DONTWAIT, NULL, NULL) = 66
13:58:57.917612 recvfrom(5, "{\"error\":\"io.systemd.Resolve.Max"..., 131080, MSG_DONTWAIT, NULL, NULL) = 66
13:58:59.417626 recvfrom(5, "{\"error\":\"io.systemd.Resolve.Max"..., 131080, MSG_DONTWAIT, NULL, NULL) = 66
13:59:00.917641 recvfrom(5, "{\"error\":\"io.systemd.Resolve.Max"..., 131080, MSG_DONTWAIT, NULL, NULL) = 66
13:59:02.417576 recvfrom(5, "{\"error\":\"io.systemd.Resolve.Max"..., 131080, MSG_DONTWAIT, NULL, NULL) = 66
13:59:03.917606 recvfrom(5, "{\"error\":\"io.systemd.Resolve.Max"..., 131080, MSG_DONTWAIT, NULL, NULL) = 66
13:59:05.417712 recvfrom(5, "{\"error\":\"io.systemd.Resolve.Max"..., 131080, MSG_DONTWAIT, NULL, NULL) = 66
13:59:06.917672 recvfrom(5, "{\"error\":\"io.systemd.Resolve.Max"..., 131080, MSG_DONTWAIT, NULL, NULL) = 66
Not that I didn't think the problem was with systemd-resolved, but this pretty much confirms it:
https://github.com/systemd/systemd/issues/28166
I don't think there is anything fping can do about this.
@cranderson: Since this is not caused by fping, can this issue be closed?
This is a longstanding issue, but I re-tested with git HEAD (a3f4c57) as of 2023-11-02 with the same results.
When using a Linux distro with systemd-resolved as the DNS resolver:
fping -g 192.168.1.0/24 takes about 10 seconds:
fping -n -g 192.168.1.0/24 is so slow that it appears to be hung. I timed it and it took longer than 5 minutes to return any output at all. All the output happened in the last 10 seconds or so of this run:
This doesn't happen if you change /etc/resolv.conf to point to an external (but still local) DNS resolver. These are the same resolvers that systemd-resolved forwards to: