$ port -d sync
Synchronizing from rsync://rsync.darwinports.org/dpupdate/dports
receiving file list ... done
./
aqua/
aqua/BiggerSQL/

[...]

rsync: mkstemp "/opt/local/var/db/dports/sources/rsync.rsync.darwinports.org_dpupdate_dports/.PortIndex.RZez0K" failed: Permission denied (13)
rsync: delete_one: unlink "/opt/local/var/db/dports/sources/rsync.rsync.darwinports.org_dpupdate_dports/net/wget/work" failed: Permission denied (13)
rsync: delete_one: unlink "/opt/local/var/db/dports/sources/rsync.rsync.darwinports.org_dpupdate_dports/devel/gettext/work" failed: Permission denied (13)

sent 8239 bytes  received 221596 bytes  51074.44 bytes/sec
total size is 12583965  speedup is 54.75
rsync error: some files could not be transferred (code 23) at /SourceCache/rsync/rsync-26/rsync/main.c(1161)
DEBUG: sync failed doing rsync
    while executing
"dportsync"
port sync failed: sync failed doing rsync