mongorestore --port 37017 -d local -c oplog.rs  ./oplog.bson
2017-04-08T20:26:12.105+0800    checking for collection data in oplog.bson
2017-04-08T20:26:12.106+0800    restoring local.oplog.rs from oplog.bson
2017-04-08T20:26:12.168+0800    Failed: local.oplog.rs: error restoring from oplog.bson: insertion error: EOF

cat error.log

2017-04-08T20:26:12.115+0800 I NETWORK  [conn6] AssertionException handling request, closing client connection: 10307 Client Error: bad object in message: bson length doesn't match what we found in object with unknown _id