doc: update helps for addnode rpc and -addnode/-maxconnections config options #21710

jonatack · 2021-04-16T19:09:15Z

Since #9319 proposed by Gregory Maxwell and released in v0.14, peers manually added through the -addnode config option or using the addnode RPC have their own separate limit of 8 connections that does not compete with other inbound or outbound connection usage and is not subject to the limitation imposed by the -maxconnections option.

This PR updates the -addnode and -maxconnections config options and the addnode RPC help docs with this information.

-addnode config option help

$ bitcoind -h | grep -A5 addnode=
  -addnode=<ip>
       Add a node to connect to and attempt to keep the connection open (see
       the addnode RPC help for more info). This option can be specified
       multiple times to add multiple nodes; connections are limited to
       8 at a time and are counted separately from the -maxconnections
       limit.

$ bitcoind -h | grep -A3 maxconnections=
  -maxconnections=<n>
       Maintain at most <n> connections to peers (default: 125). This limit
       does not apply to connections manually added via -addnode or the
       addnode RPC, which have a separate limit of 8.

addnode rpc help

$ bitcoin-cli help addnode
addnode "node" "command"

Attempts to add or remove a node from the addnode list.
Or try a connection to a node once.
Nodes added using addnode (or -connect) are protected from DoS disconnection and are not required to be
full nodes/support SegWit as other outbound peers are (though such peers will not be synced from).
Addnode connections are limited to 8 at a time and are counted separately from the -maxconnections limit.

ghost · 2021-04-16T22:18:51Z

Interesting. I didn't know -addnode had any separate limits. Concept ACK.

Will have to test today and maybe ask related questions here or SE or Reddit.

jonatack · 2021-04-17T09:16:27Z

Interesting. I didn't know -addnode had any limits. Concept ACK.

Thanks @prayank23. Indeed, as it's not documented AFAIK except in the 0.14 release notes a few years back, I imagine that many users won't ever know unless they look into the codebase, e.g. in net.h

static const int MAX_ADDNODE_CONNECTIONS = 8;

and then verifying how the constant is used, or they infer it by using -netinfo with more than 8 addnode peers configured and seeing that the number of manual connections never exceeds 8 (or by using getpeerinfo with jq).

ghost · 2021-04-17T16:55:42Z

I imagine that many users won't ever know unless they look into the codebase, e.g. in net.h

Maybe I missed it when I was experimenting with outgoing connections few days back: https://bitcoin.stackexchange.com/questions/103753/increase-maximum-number-of-outgoing-connections-for-full-node

I should have tried addnode to get more outgoing connections.

Not sure what's the best way to test this. I tried adding random nodes from https://bitnodes.io/nodes/?q=United%20States using addnode RPC in Bitcoin Core (Mainnet). Looking at the total number of outgoing connections: 13 which is more than 10 I can verify addnode has separate limits that do not compete with other inbound or outbound connection usage.

Added maxconnections=4 in bitcoin.conf, relaunched Bitcoin Core, tried adding random nodes from above link and it worked as expected (I could see more than 4 peers connected) and mentioned in b4fcbcf

jonatack · 2021-04-17T18:30:31Z

@prayank23 thanks for having a look. If you run a node with more than 8 -addnode peers (you can get a list of, say, 20 peers from your addrman if needed with bitcoin-cli getnodeaddresses 20), you'll never see more than 8 connections in the "manual" column of cli -netinfo:

        ipv4    ipv6   onion     i2p   total   block  manual
in         0       0       1       0       1
out        4       0      10       4      18       2       8
total      4       0      11       4      19

Codewise, I suggest looking at the code returned by git grep nMaxAddnode -- there are only six lines.

jarolrod

ACK b4fcbcf

Looks good to me. Documenting in the help that addnode connections are counted separately from maxconnections is useful context to add.

jonatack · 2021-04-18T13:41:51Z

Thanks @jarolrod!

If anyone is curious, the separate connections limit for addnode peers was added by @gmaxwell in #9319. I've added the PR link to the PR description.

jonatack · 2021-04-18T15:39:55Z

I was experimenting with outgoing connections few days back: https://bitcoin.stackexchange.com/questions/103753/increase-maximum-number-of-outgoing-connections-for-full-node

I should have tried addnode to get more outgoing connections.

FWIW, I found #6014 to be an interesting discussion about connection counts.

ghost · 2021-04-18T20:08:10Z

ACK b4fcbcf

FWIW, I found #6014 to be an interesting discussion about connection counts.

Thanks for sharing the link. I have 3 follow up questions after reading few things in that PR:

If more than 8 outgoing connections are bad for the network, can we at least have one option in bitcoin.conf to reduce this to something below 8 if the user wants to? Maybe keep Default=8, MIN=2, MAX=8 and OUTBOUND_FULL_RELAY_CONNECTIONS can be anything between 2 and 8.
If the user can add more outgoing connections using addnode which has a separate limit so total number of full relay outgoing connections can be more than 8, is this okay and does not the involve the risks mentioned in Add a -maxoutbound option for use on pool servers to increase bitcoin network connectivity. #6014 ?
How did we decide this number 8? Why is it not 7 or 9?

jonatack · 2021-04-18T20:25:27Z

If more than 8 outgoing connections are bad for the network, can we at least have one option in bitcoin.conf to reduce this to something below 8 if the user wants to?

See #4687.

DrahtBot · 2021-04-30T12:21:23Z

The following sections might be updated with supplementary metadata relevant to reviewers and maintainers.

Conflicts

No conflicts as of last run.

…maxconnections config options b4fcbcf doc: update -maxconnections config option help (Jon Atack) 79685a8 doc: update -addnode config option help (Jon Atack) 2896c6c doc: update addnode rpc help (Jon Atack) Pull request description: Since bitcoin#9319 proposed by Gregory Maxwell and released in v0.14, peers manually added through the `-addnode` config option or using the `addnode` RPC have their own separate limit of 8 connections that does not compete with other inbound or outbound connection usage and is not subject to the limitation imposed by the `-maxconnections` option. This PR updates the `-addnode` and `-maxconnections` config options and the `addnode` RPC help docs with this information. `-addnode` config option help ``` $ bitcoind -h | grep -A5 addnode= -addnode=<ip> Add a node to connect to and attempt to keep the connection open (see the addnode RPC help for more info). This option can be specified multiple times to add multiple nodes; connections are limited to 8 at a time and are counted separately from the -maxconnections limit. $ bitcoind -h | grep -A3 maxconnections= -maxconnections=<n> Maintain at most <n> connections to peers (default: 125). This limit does not apply to connections manually added via -addnode or the addnode RPC, which have a separate limit of 8. ``` `addnode` rpc help ``` $ bitcoin-cli help addnode addnode "node" "command" Attempts to add or remove a node from the addnode list. Or try a connection to a node once. Nodes added using addnode (or -connect) are protected from DoS disconnection and are not required to be full nodes/support SegWit as other outbound peers are (though such peers will not be synced from). Addnode connections are limited to 8 at a time and are counted separately from the -maxconnections limit. ``` ACKs for top commit: prayank23: ACK bitcoin@b4fcbcf jarolrod: ACK b4fcbcf Tree-SHA512: b6d69baa6cbf6d53f91bac5b39b549d49db6c95f92ea1bdd3588a6432794a25ac2c8b3c89e2c72bb9097e61f2717c8b5ecc404745d5992b88e523db03200898f

jonatack added 2 commits April 16, 2021 20:39

doc: update addnode rpc help

2896c6c

doc: update -addnode config option help

79685a8

DrahtBot added the RPC/REST/ZMQ label Apr 16, 2021

doc: update -maxconnections config option help

b4fcbcf

jonatack changed the title ~~doc: update help docs for -addnode config option and addnode rpc~~ doc: update helps for addnode rpc and -addnode/-maxconnections config options Apr 17, 2021

ghost mentioned this pull request Apr 17, 2021

doc: update reduce-memory.md and bitcoin.conf -maxconnections info #21709

Merged

jarolrod reviewed Apr 18, 2021

View reviewed changes

DrahtBot mentioned this pull request Apr 30, 2021

Add -maxoutfullrelay #21815

Closed

laanwj merged commit b8b6801 into bitcoin:master May 5, 2021

jonatack deleted the update-addnode-docs branch May 5, 2021 15:02

ghost mentioned this pull request Jul 20, 2021

p2p connection failure when setting maxconnections romanz/electrs#429

Closed

gwillen pushed a commit to ElementsProject/elements that referenced this pull request Jun 1, 2022

Merge b8b6801 into merged_master (Bitcoin PR bitcoin/bitcoin#21710)

b20d4cb

bitcoin locked as resolved and limited conversation to collaborators Aug 16, 2022

Provide feedback

Saved searches

Use saved searches to filter your results more quickly

Uh oh!

doc: update helps for addnode rpc and -addnode/-maxconnections config options #21710

doc: update helps for addnode rpc and -addnode/-maxconnections config options #21710

Uh oh!

jonatack commented Apr 16, 2021 •

edited

Loading

Uh oh!

ghost commented Apr 16, 2021 •

edited by ghost

Loading

Uh oh!

jonatack commented Apr 17, 2021

Uh oh!

ghost commented Apr 17, 2021

Uh oh!

jonatack commented Apr 17, 2021

Uh oh!

jarolrod left a comment

Uh oh!

jonatack commented Apr 18, 2021

Uh oh!

jonatack commented Apr 18, 2021

Uh oh!

ghost commented Apr 18, 2021

Uh oh!

jonatack commented Apr 18, 2021

Uh oh!

DrahtBot commented Apr 30, 2021 •

edited

Loading

Uh oh!

Reviewers

Assignees

Labels

Projects

Milestone

Development

Uh oh!

4 participants

doc: update helps for addnode rpc and -addnode/-maxconnections config options #21710

doc: update helps for addnode rpc and -addnode/-maxconnections config options #21710

Uh oh!

Conversation

jonatack commented Apr 16, 2021 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Uh oh!

ghost commented Apr 16, 2021 • edited by ghost Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Uh oh!

jonatack commented Apr 17, 2021

Uh oh!

ghost commented Apr 17, 2021

Uh oh!

jonatack commented Apr 17, 2021

Uh oh!

jarolrod left a comment

Choose a reason for hiding this comment

Uh oh!

jonatack commented Apr 18, 2021

Uh oh!

jonatack commented Apr 18, 2021

Uh oh!

ghost commented Apr 18, 2021

Uh oh!

jonatack commented Apr 18, 2021

Uh oh!

DrahtBot commented Apr 30, 2021 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Conflicts

Uh oh!

Reviewers

Assignees

Labels

Projects

Milestone

Development

Uh oh!

4 participants

jonatack commented Apr 16, 2021 •

edited

Loading

ghost commented Apr 16, 2021 •

edited by ghost

Loading

DrahtBot commented Apr 30, 2021 •

edited

Loading