Stuck on remote rsync with BackupPC and openrsync

Hi,

I have been trying to get BackupPC 3.3.2 running on a Debian 10/Buster
server to back up my OpenBSD 6.6 router. It works fine with the GNU
rsync port on the OpenBSD box but when I try to use the native
openrsync instead, it just seems to not get started properly and hangs.

On the Debian side, it looks like this until I kill it after a few
hours:


$ /usr/bin/perl /usr/share/backuppc/bin/BackupPC_dump -v milan
cmdSystemOrEval: about to system /bin/ping -c 1 172.16.10.1
cmdSystemOrEval: finished: got output PING 172.16.10.1 (172.16.10.1)
56(84) bytes of data. 64 bytes from 172.16.10.1: icmp_seq=1 ttl=255
time=0.173 ms

--- 172.16.10.1 ping statistics ---
1 packets transmitted, 1 received, 0% packet loss, time 0ms
rtt min/avg/max/mdev = 0.173/0.173/0.173/0.000 ms

cmdSystemOrEval: about to system /bin/ping -c 1 172.16.10.1
cmdSystemOrEval: finished: got output PING 172.16.10.1 (172.16.10.1)
56(84) bytes of data. 64 bytes from 172.16.10.1: icmp_seq=1 ttl=255
time=0.094 ms

--- 172.16.10.1 ping statistics ---
1 packets transmitted, 1 received, 0% packet loss, time 0ms
rtt min/avg/max/mdev = 0.094/0.094/0.094/0.000 ms

CheckHostAlive: returning 0.094
full backup started for directory / (baseline backup #135)
started full dump, share=/
Running: /usr/bin/ssh -q -x -o
UserKnownHostsFile=/etc/backuppc/ssh/known_hosts
-i /etc/backuppc/ssh/id_ed25519 -l backup 172.16.10.1
doas /usr/local/bin/rsync --server --sender --numeric-ids --perms
--owner --group -D --links --times --recursive -x --ignore-times . /
Xfer PIDs are now 10093
xferPids 10093
Got remote protocol 27
Negotiated protocol version 27



milan/172.16.10.1 is the OpenBSD box to be backed up. BackupPC connects
via ssh and starts openrsync in server mode. /usr/local/bin/rsync is a
wrapper script that removes the "--ignore-times" parameter before it
invokes openrsync because openrsync does not understand that parameter
and BackupPC insists on adding that parameter.

On the OpenBSD box I see the following processes until I kill them
after a few hours:

USER PID PPID PGID SESS JOBC STAT TT TIME
COMMAND

backup 22274 23311 23311 fffffd8073138850 0 I ?? 0:00.12
sshd: backup@notty (sshd)

backup 98017 22274 98017 fffffd80731388c0 0 Ip ?? 0:00.05
sh -c doas /usr/local/bin/rsync --server --sender --numeric-ids --perms
--owner --group -D --links --times --recursive -x --ignore-times . /

root 95559 98017 98017 fffffd80731388c0 0 Ip ?? 0:00.01
/bin/ksh /usr/local/bin/rsync --server --sender --numeric-ids
--perms --owner --group -D --links --times --recursive -x
--ignore-times . /

root 15271 95559 98017 fffffd80731388c0 0 IpU ?? 0:00.28
/usr/bin/openrsync --server --sender --numeric-ids --perms
--owner --group -D --links --times --recursive -x . /



A ktrace -dig 98017 just gives me an empty trace file (it starts to
have something when I kill the processes but that obviously does not
tell me what went wrong initially).

Any suggestions what might go wrong or how to debug this further?

Fabian