To reproduce:

1) Start a replica set
2) Pump in 50~60 millions of documents so we have plenty oplog entries.
3) Start another replica set listening on port 27018
4) Run mongooplog to migrate the oplog

Expected:
Command success, oplog is copied and applied on destination machine.

Actual: Timeout getting oplog query:

MacBook-Pro-13:data tjworks$ mongooplog --from localhost:27017 --host localhost:27018 -vvv
2014-09-04T23:01:57.162+0800 creating new connection to:localhost:27018
2014-09-04T23:01:57.162+0800 [ConnectBG] BackgroundJob starting: ConnectBG
2014-09-04T23:01:57.163+0800 connected to server localhost:27018 (127.0.0.1)
2014-09-04T23:01:57.163+0800 connected connection!
connected to: localhost:27018
2014-09-04T23:01:57.163+0800 going to connect
2014-09-04T23:01:57.163+0800 [ConnectBG] BackgroundJob starting: ConnectBG
2014-09-04T23:01:57.163+0800 [oplogreplay] connected to server localhost:27017 (127.0.0.1)
2014-09-04T23:01:57.163+0800 connected
2014-09-04T23:01:57.163+0800 starting from Sep 3 23:01:57:0
2014-09-04T23:01:57.163+0800 [oplogreplay] repl: local.oplog.rs.find({ ts:

{ $gte: Timestamp 1409756517000|0 }

})
2014-09-04T23:02:27.166+0800 [oplogreplay] Socket recv() timeout 127.0.0.1:27017
2014-09-04T23:02:27.169+0800 [oplogreplay] SocketException: remote: 127.0.0.1:27017 error: 9001 socket exception [RECV_TIMEOUT] server [127.0.0.1:27017]
2014-09-04T23:02:27.169+0800 [oplogreplay] DBClientCursor::init call() failed
2014-09-04T23:02:27.169+0800 [oplogreplay] User Assertion: 15910:Doesn't have cursor for reading oplog
assertion: 15910 Doesn't have cursor for reading oplog
MacBook-Pro-13:data tjworks$ mongo

rs:PRIMARY> db.oplog.rs.stats()
{
"ns" : "local.oplog.rs",
"count" : 46160528,
"size" : 14990072156,
"avgObjSize" : 324,
"storageSize" : 15728643984,
"numExtents" : 9,
"nindexes" : 0,
"lastExtentSize" : 4096,
"paddingFactor" : 1,
"systemFlags" : 0,
"userFlags" : 0,
"totalIndexSize" : 0,
"indexSizes" : {

},
"capped" : true,
"max" : NumberLong("9223372036854775807"),
"ok" : 1
}
rs:PRIMARY> db.printReplicationInfo()
configured oplog size: 15000MB
log length start to end: 869784secs (241.61hrs)
oplog first event time: Mon Aug 25 2014 21:27:54 GMT+0800 (HKT)
oplog last event time: Thu Sep 04 2014 23:04:18 GMT+0800 (HKT)
now: Thu Sep 04 2014 23:04:19 GMT+0800 (HKT)
rs:PRIMARY>