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81 lines
3.0 KiB
Markdown
81 lines
3.0 KiB
Markdown
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# [ngIRCd](https://ngircd.barton.de) - SSL/TLS Encrypted Connections
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ngIRCd supports SSL/TLS encrypted connections using the *OpenSSL* or *GnuTLS*
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libraries. Both encrypted server-server links as well as client-server links
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are supported.
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SSL is a compile-time option which is disabled by default. Use one of these
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options of the ./configure script to enable it:
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- `--with-openssl`: enable SSL support using OpenSSL.
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- `--with-gnutls`: enable SSL support using GnuTLS.
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You can check the output of `ngircd --version` to validate if your executable
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includes support for SSL or not: "+SSL" must be listed in the feature flags.
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You also need a SSL key and certificate, for example using Let's Encrypt, which
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is out of the scope of this document.
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From a feature point of view, ngIRCds support for both libraries is
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comparable. The only major difference (at this time) is that ngIRCd with GnuTLS
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does not support password protected private keys.
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## Configuration
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SSL-encrypted connections and plain-text connects can't run on the same network
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port (which is a limitation of the IRC protocol); therefore you have to define
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separate port(s) in your `[SSL]` block in the configuration file.
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A minimal configuration for *accepting* SSL-encrypted client & server
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connections looks like this:
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``` ini
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[SSL]
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CertFile = /etc/ssl/certs/my-fullchain.pem
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KeyFile = /etc/ssl/certs/my-privkey.pem
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Ports = 6697, 6698
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```
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In this case, the server only deals with *incoming* connections and never has to
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validate SSL certificates itself, and therefore no "Certificate Authorities" are
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needed.
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If you want to use *outgoing* SSL-connections to other servers, you need to add:
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``` ini
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[SSL]
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...
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CAFile = /etc/ssl/certs/ca-certificates.crt
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DHFile = /etc/ngircd/dhparams.pem
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[SERVER]
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...
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SSLConnect = yes
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```
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The `CAFile` option configures a file listing all the certificates of the
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trusted Certificate Authorities.
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The Diffie-Hellman parameters file `dhparams.pem` can be created like this:
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- OpenSSL: `openssl dhparam -2 -out /etc/ngircd/dhparams.pem 4096`
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- GnuTLS: `certtool --generate-dh-params --bits 4096 --outfile /etc/ngircd/dhparams.pem`
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Note that enabling `SSLConnect` not only enforces SSL-encrypted links for
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*outgoing* connections to other servers, but for *incoming* connections as well:
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If a server configured with `SSLConnect = yes` tries to connect on a plain-text
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connection, it won't be accepted to prevent data leakage! Therefore you should
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set this for *all* servers you expect to use SSL-encrypted connections!
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## Accepting untrusted Remote Certificates
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If you are using self-signed certificates or otherwise invalid certificates,
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which ngIRCd would reject by default, you can force ngIRCd to skip certificate
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validation on a per-server basis and continue establishing outgoing connections
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to the respective peer by setting `SSLVerify = no` in the `[SERVER]` block of
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this remote server in your configuration.
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But please think twice before doing so: the established connection is still
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encrypted but the remote site is *not verified at all* and man-in-the-middle
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attacks are possible!
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