Unfortunately I had to time box myself from this issue while doing initial investigation...
I was able to reproduce the issue: after installing openbsd-inetd, tcpd and rstatd + rstat-client I could observe that only xenial and bionic hosts are the ones responding to UDP broadcast requests from "rup" binary: (c)rafaeldtinoco@xenial:~$ rup xenial.lxd 20:09 up 1:39, load 0.58 0.63 0.54 bionic.lxd 20:09 up 1:43, load 0.58 0.63 0.54 (c)rafaeldtinoco@bionic:~$ rup xenial.lxd 20:12 up 1:42, load 0.39 0.50 0.51 bionic.lxd 20:12 up 1:46, load 0.39 0.50 0.51 (c)rafaeldtinoco@eoan:~$ sudo rup xenial.lxd 20:12 up 1:51, load 0.62 0.52 0.49 bionic.lxd 20:12 up 1:55, load 0.62 0.52 0.49 (c)rafaeldtinoco@focal:~$ rup xenial.lxd 20:12 up 1:42, load 0.28 0.46 0.50 bionic.lxd 20:12 up 1:47, load 0.28 0.46 0.50 So it is clear that the rpc-rstatd is the one to blame, as all clients can receive info from older ubuntu versions. I was curious because there were practically no changes in all related packages: - openbsd-inetd - tcpd (tcp-wrappers) - rstatd to justify a change of behavior so I checked syslog in the working nodes: ---- when hostname is given: xenial rpc.rstatd[2961]: connect from 10.250.97.142 (10.250.97.142) when broadcast is attempted: xenial rpc.rstatd[2965]: connect from 127.0.0.1 (127.0.0.1) and when broadcast is attempted with remote bionic (works): bionic rpc.rstatd[6264]: connect from 127.0.0.1 (127.0.0.1) bionic rpc.rstatd[6267]: connect from 127.0.0.1 (127.0.0.1) ---- and there might be something related to UDP broadcast and lo interface... I backported: openbsd-inetd 0.20160825-4build1 tcpd 7.6.q-30 rstatd 4.0.1-10 to bionic expecting to brake it and it did not happen =). As I was running all as containers, on top of the same kernel, it is likely some environmental thing related to how tcp-wrappers are dealing with an UDP socket listening to broadcast. ---- Running inetd by hand (outside systemd scope) did not help also, the broadcast request did not even arrive to the socket as it seems, just the direct one: (c)rafaeldtinoco@eoan:~$ sudo inetd -idl pmap_set: 100001 1 17 41139 pmap_set: 100001 2 17 41139 pmap_set: 100001 3 17 41139 pmap_set: 100001 4 17 41139 pmap_set: 100001 5 17 41139 ADD: rstatd rpcprog=100001, rpcvers=5/1, proto=rpc/udp, wait.max=1.256 user:group=nobody:(default) builtin=0 server=/usr/sbin/tcpd someone wants rstatd 2830 execv /usr/sbin/tcpd reaping asked for 2830 reaped, status 0 restored rstatd, fd 7 pmap_unset(100001, 1) pmap_unset(100001, 2) pmap_unset(100001, 3) pmap_unset(100001, 4) pmap_unset(100001, 5) ---- Checking tcpdump: $ rup eoan.lxd and the eoan container shows: 20:46:39.145376 IP 10.250.97.227.57183 > 10.250.97.200.111: UDP, length 56 20:46:39.145486 IP 10.250.97.200.111 > 10.250.97.227.57183: UDP, length 28 20:46:39.145562 IP 10.250.97.227.51090 > 10.250.97.200.60135: UDP, length 40 20:46:39.150911 IP 10.250.97.200.60135 > 10.250.97.227.51090: UDP, length 132 $ rup with no args and eoan container shows: 20:46:42.906008 IP 10.250.97.227.42901 > 10.250.97.255.111: UDP, length 100 meaning that the broadcast address was simply ignored by eoan as it looks like, while it was fully responded by the xenial container: 20:49:45.199018 IP 10.250.97.227.44449 > 10.250.97.255.111: UDP, length 100 20:49:45.204090 IP 10.250.97.213.713 > 10.250.97.227.44449: UDP, length 140 ---- The only way I was able to reproduce something similar was if daemon side was not listening (or have bind) the broadcast address... My "tests" were done using netcat like: # client (c)rafaeldtinoco@eoan:~$ nc -b -u 10.250.97.255 8080 one two three # server (c)rafaeldtinoco@bionic:~$ sudo nc -D -k -l -s 10.250.97.255 -p 8080 -u -b one two three ---- Still need to figure what takes rpc.statd not to bind broadcast address in newer Ubuntu versions. -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1890276 Title: inetd does not answer broadcast requests To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/openbsd-inetd/+bug/1890276/+subscriptions -- ubuntu-bugs mailing list [email protected] https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
