When a handshake fails, it can fail due to timeout or destroyed
connection, in which case the connection will be, or already is,
closed, and we don't want to do it twice.
Additionally, when closing a connection directly from the top
level code, ensure the connection is gone from the m_connects
list so it won't be used again.
AFAICT this is now clean in netstat, /proc/PID/fd and print_cn.
This fixes a noisy (but harmless) exception.
- New flag in NOTIFY_NEW_TRANSACTION to indicate stem mode
- Stem loops detected in tx_pool.cpp
- Embargo timeout for a blackhole attack during stem phase
4771a7ae p2p: remove obsolete local time in handshake (moneromooo-monero)
2fbbc4a2 p2p: avoid sending the same peer list over and over (moneromooo-monero)
3004835b epee: remove backward compatible endian specific address serialization (moneromooo-monero)
39a343d7 p2p: remove backward compatible peer list (moneromooo-monero)
60631802 p2p: simplify last_seen serialization now we have optional stores (moneromooo-monero)
9467b2e4 cryptonote_protocol: omit top 64 bits of difficulty when 0 (moneromooo-monero)
b595583f serialization: do not write optional fields with default value (moneromooo-monero)
5f98b46d p2p: remove obsolete local time from TIMED_SYNC (moneromooo-monero)
During the handshake for an incoming connection, the peer id is checked against the local node's peer id only for the specific zone of the incoming peer, in order to avoid linking public addresses to tor addresses:
5d7ae2d279/src/p2p/net_node.inl (L2343)
However, on handshakes for outgoing connections, all zones are checked:
5d7ae2d279/src/p2p/net_node.inl (L1064)
If an attacker wanted to link a specific tor node to a public node, they could potentially connect to as many public nodes as possible, get themselves added to the peer whitelist, maybe stuff some more attacker-owned addresses into the greylist, then disconnect, and for any future incoming connections, respond with the tor node's id in an attempt to link the public/tor addresses.
Nodes remember which connections have been sent which peer addresses
and won't send it again. This causes more addresses to be sent as
the connection lifetime grows, since there is no duplication anymore,
which increases the diffusion speed of peer addresses. The whole
white list is now considered for sending, not just the most recent
seen peers. This further hardens against topology discovery, though
it will more readily send peers that have been last seen earlier
than it otherwise would. While this does save a fair amount of net
bandwidth, it makes heavy use of std::set lookups, which does bring
network_address::less up the profile, though not too aggressively.
Daemons intended for public use can be set up to require payment
in the form of hashes in exchange for RPC service. This enables
public daemons to receive payment for their work over a large
number of calls. This system behaves similarly to a pool, so
payment takes the form of valid blocks every so often, yielding
a large one off payment, rather than constant micropayments.
This system can also be used by third parties as a "paywall"
layer, where users of a service can pay for use by mining Monero
to the service provider's address. An example of this for web
site access is Primo, a Monero mining based website "paywall":
https://github.com/selene-kovri/primo
This has some advantages:
- incentive to run a node providing RPC services, thereby promoting the availability of third party nodes for those who can't run their own
- incentive to run your own node instead of using a third party's, thereby promoting decentralization
- decentralized: payment is done between a client and server, with no third party needed
- private: since the system is "pay as you go", you don't need to identify yourself to claim a long lived balance
- no payment occurs on the blockchain, so there is no extra transactional load
- one may mine with a beefy server, and use those credits from a phone, by reusing the client ID (at the cost of some privacy)
- no barrier to entry: anyone may run a RPC node, and your expected revenue depends on how much work you do
- Sybil resistant: if you run 1000 idle RPC nodes, you don't magically get more revenue
- no large credit balance maintained on servers, so they have no incentive to exit scam
- you can use any/many node(s), since there's little cost in switching servers
- market based prices: competition between servers to lower costs
- incentive for a distributed third party node system: if some public nodes are overused/slow, traffic can move to others
- increases network security
- helps counteract mining pools' share of the network hash rate
- zero incentive for a payer to "double spend" since a reorg does not give any money back to the miner
And some disadvantages:
- low power clients will have difficulty mining (but one can optionally mine in advance and/or with a faster machine)
- payment is "random", so a server might go a long time without a block before getting one
- a public node's overall expected payment may be small
Public nodes are expected to compete to find a suitable level for
cost of service.
The daemon can be set up this way to require payment for RPC services:
monerod --rpc-payment-address 4xxxxxx \
--rpc-payment-credits 250 --rpc-payment-difficulty 1000
These values are an example only.
The --rpc-payment-difficulty switch selects how hard each "share" should
be, similar to a mining pool. The higher the difficulty, the fewer
shares a client will find.
The --rpc-payment-credits switch selects how many credits are awarded
for each share a client finds.
Considering both options, clients will be awarded credits/difficulty
credits for every hash they calculate. For example, in the command line
above, 0.25 credits per hash. A client mining at 100 H/s will therefore
get an average of 25 credits per second.
For reference, in the current implementation, a credit is enough to
sync 20 blocks, so a 100 H/s client that's just starting to use Monero
and uses this daemon will be able to sync 500 blocks per second.
The wallet can be set to automatically mine if connected to a daemon
which requires payment for RPC usage. It will try to keep a balance
of 50000 credits, stopping mining when it's at this level, and starting
again as credits are spent. With the example above, a new client will
mine this much credits in about half an hour, and this target is enough
to sync 500000 blocks (currently about a third of the monero blockchain).
There are three new settings in the wallet:
- credits-target: this is the amount of credits a wallet will try to
reach before stopping mining. The default of 0 means 50000 credits.
- auto-mine-for-rpc-payment-threshold: this controls the minimum
credit rate which the wallet considers worth mining for. If the
daemon credits less than this ratio, the wallet will consider mining
to be not worth it. In the example above, the rate is 0.25
- persistent-rpc-client-id: if set, this allows the wallet to reuse
a client id across runs. This means a public node can tell a wallet
that's connecting is the same as one that connected previously, but
allows a wallet to keep their credit balance from one run to the
other. Since the wallet only mines to keep a small credit balance,
this is not normally worth doing. However, someone may want to mine
on a fast server, and use that credit balance on a low power device
such as a phone. If left unset, a new client ID is generated at
each wallet start, for privacy reasons.
To mine and use a credit balance on two different devices, you can
use the --rpc-client-secret-key switch. A wallet's client secret key
can be found using the new rpc_payments command in the wallet.
Note: anyone knowing your RPC client secret key is able to use your
credit balance.
The wallet has a few new commands too:
- start_mining_for_rpc: start mining to acquire more credits,
regardless of the auto mining settings
- stop_mining_for_rpc: stop mining to acquire more credits
- rpc_payments: display information about current credits with
the currently selected daemon
The node has an extra command:
- rpc_payments: display information about clients and their
balances
The node will forget about any balance for clients which have
been inactive for 6 months. Balances carry over on node restart.
