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PyLink FAQ

Startup errors

I get errors like "ImportError: No module named 'yaml'" when I start PyLink

You are missing dependencies - re-read

I get errors like "yaml.scanner.ScannerError: while scanning for the next token, found character '\t' that cannot start any token"

You must use spaces and not tabs to indent your configuration file! (\t is the escaped code for a tab, which is not allowed in YAML)

I get errors like "ParserError: while parsing a block mapping ... expected <block end>, but found '<block sequence start>'

This likely indicates an indentation issue. When you create a list in YAML (PyLink's config format), all entries must be indented consistently. For example, this is bad:

# This will cause an error!
    - abcd
    - def
  - ghi

This is good:

    - abcd
    - def
    - ghi

I keep getting YAML / syntax errors trying to set up my instance!

Take a few minutes to familiarize yourself with YAML, the markup language we use for the config file. CraftIRC, Ansible, and Wikipedia all provide excellent guides (with examples) on its basic structure.

A common misconception is that the YAML format is something specific to Python or PyLink, but this is not the case! YAML is a programming language-independent standard which happens to use indents for structures like Python does, but parsers for it exist just about everywhere.

The reason I (James) chose it for this project is essentially a restatement of its common benefits:

  • It's compact and human readable (compared to raw JSON or XML)
  • It's powerful, supporting everything from nested config blocks to multi-line strings
  • It fits well in the Python landscape, compared to a flat .ini or C-style config format
  • It's language independent, which means it's not a giant pain if we decide to rewrite the project in some other language one day... 🙃

Linking / Connection issues

PyLink won't connect to my network!

As a general guide, you should check the following before asking for help:

  • Is the target network's IRCd showing failed connection attempts?
    • If not:

      1. Is PyLink connecting to the right port (i.e. one the IRCd is listening on?)
      2. Is the target network's IRCd actually binding to the port you're trying to use? If there is a port conflict with another program, the IRCd may fail to bind to specific ports but still start on others which are free.
      3. Is the target port firewalled on the target machine?
      4. Is there a working connection between the source and target servers? Use ping to test this, as routing issues between providers can cause servers to become unreachable.
        • If your servers purposely block ping, you're going to have to figure this one out yourself... 😬
    • If so:

      1. Check for recvpass/sendpass/server hostname/IP mismatches - usually the IRCd will tell you if you're running into one of these, provided you have the right server notices enabled (consult your IRCd documentation for how to enable these).
      2. Make sure you're not connecting with SSL on a non-SSL port, or vice versa.

If these steps haven't helped you so far, maybe you've found a bug...?

My networks keep disconnecting with SSL errors!

See - the problem appears to be caused somewhere in Python's SSL stack and/or OpenSSL, and not directly by our code.

Unfortunately, the only workarounds so far are to either disable SSL/TLS, or wrap a plain IRC connection in an external service (stunnel, OpenVPN, etc.)

I turned autoconnect for PyLink on, and now I'm getting errors!

PyLink does not support inbound connections - much like regular services such as Atheme or Anope, it only connects outwards to IRCds. (If you don't understand what this means, it means you should turn autoconnect off for PyLink)

Relay issues

Does everyone need to install PyLink Relay for it to work?

No! Only the PyLink administrator needs to host a PyLink instance with the relay plugin loaded, as each instance can connect to multiple networks. Everyone else only needs to add a link block on their IRCd.

InterJanus-style links between PyLink daemons are not supported yet; see for any progress regarding that.

What are PyLink's advantages over Janus?

PyLink provides, in no particular order:

  • More complete support for modern IRCds (UnrealIRCd 4.x, InspIRCd 2.0, charybdis 4, Nefarious IRCu, etc.).
  • A flexible, maintainable codebase extensible beyond Relay.
  • Proper protocol negotiation leading to fewer SQUIT/DoS possibilities:
    • Better support for channel modes such as +fjMOR, etc.
    • Proper support for nick length limits with relayed users.

My IRCd SQUITs the Relay server with errors like "Bad nickname introduced"!

First, check whether the SQUIT message includes the nick that triggered the netsplit. If this nick includes any characters not allowed in regular IRC, such as the slash ("/"), or is otherwise an invalid nick (e.g. beginning with a hyphen or number), this likely indicates a bug in PyLink Relay. These problems should be reported on the issue tracker.

However, if the nick mentioned is legal on IRC, this issue is likely caused by a max nick length misconfiguration: i.e. the Relay server is introducing nicks too long for the target network. This can be fixed by setting the maxnicklen option in the affected network's PyLink server: block to the same value as that network's 005 NICKLEN (that is, the NICKLEN=<num> value in /raw version).

Clientbot doesn't relay both ways!

Load the relay_clientbot plugin.

How do I turn off colors in Clientbot?

See, especially the section "Disabling Colors/Control Codes".

Relay is occasionally dropping users from channels!

This usually indicates a serious bug in either Relay or PyLink's protocol modules, and should be reported as an issue. When asking for help, please state which IRCds your PyLink instance is linking to: specifically, which IRCd the missing users are from and which IRCd the users are missing on. Also, be prepared to send debug logs as you reproduce the issue!

  • Another tip in debugging this is to run showchan on the affected channels. If PyLink shows users in showchan that aren't in the actual user list, this is most likely a protocol module issue. If showchan's output is correct, it is instead probably a Relay issue where users aren't spawning correctly.

Does Relay support mode +R, +M, etc.? How does Relay handle modes supported on one IRCd but not on another?

Essentially, PyLink maps IRCd modes together by name, so modes that use different characters on different IRCds can be recognized as the same "mode". Tables of supported channel modes, user modes, and extbans (in 2.0+) can be found at Note that third party/contrib modules implementing modes are generally not tested / supported.

Relay in particular uses whitelists to determine which modes are safe to relay: for 2.0.0, this is Most channel modes recognized by PyLink are whitelisted and usable with Relay, with the following exceptions:

  • "registered" channel / user modes (InspIRCd, UnrealIRCd +r) - this is to prevent conflicts with local networks's services.
  • "permanent" channel modes (commonly +P) - it's not necessary for remote networks' channels to also be permanent locally.
  • Flood protection modes are only relayed between networks running the same IRCd (UnrealIRCd <-> UnrealIRCd or InspIRCd <-> InspIRCd).
  • Modes and extbans that specify a forwarding channel - mangling channel names between networks is far too complicated and desync prone.
  • InspIRCd's m_ojoin +Y and m_operprefix +y are ignored by Relay.
  • auditorium (InspIRCd +u), delayjoin (UnrealIRCd, P10, InspIRCd +D), and any other modes affecting join visibilites are not supported.

Support for user modes is not as complete:

  • Filter type modes such as callerid (+g), regonly (+R), noctcp (UnrealIRCd +T) are not yet supported by Relay.
  • Service protection modes (UnrealIRCD +S, InspIRCd +k, etc.) are not forwarded by Relay to prevent abuse.

How does Relay handle kills?


How does Relay handle KLINE/GLINE/ZLINE?

It doesn't. explains my reasons for skipping over this:

  • The weakest link, whether this be a malicious/compromised/mistaken oper or a misconfigured services instance, can easily wreak havoc by banning something they shouldn't.
  • KLINE relaying goes against the concept of partial network links and creates serious animosity when opers disagree on policy. If KLINEs are shared, opers are essentially shared as well, and this is not the goal of Relay.

Services issues

Service bots aren't spawning on my network, even though PyLink connects

This indicates either a bug in PyLink's protocol module or (less commonly) a bug in your IRCd. Hint: ENDBURST is likely not being sent or received properly, which causes service bot spawning to never trigger.

Make sure you're using an officially supported IRCd before requesting help, as custom IRCd code can potentially trigger S2S bugs and is not something we can support.