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# Sslh

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This article or section is a candidate for merging with List of applications/Security.

Notes: Roughly duplicates upstream documentation, does not even explain in which use case this is interesting or applicable. (Discuss in Talk:Sslh)

sslh is a ssl/ssh multiplexer.

## Installation

Install the sslh package.

## Configuration

The default configuration file is located at `/etc/sslh.cfg`, which supports `ssh`, `openvpn`, `xmpp`, `http`, `ssl`, and `anyprot` protocols.

2 additional configuration files are included in the package:

- `/usr/share/doc/sslh/basic.cfg`, which is a basic configuration file that should provide sensible values for "standard" setup.
- `/usr/share/doc/sslh/example.cfg`, which is provided as documentation to show what is possible. It should not be used as-is, and probably should not be used as a starting point for a working configuration.

## Usage

Start/enable `sslh-fork.service` or `sslh-select.service`, depending on which option is right for your server:

- `sslh-fork` forks a new process for each incoming connection. It is well-tested and very reliable, but incurs the overhead of many processes. If you're going to use `sslh` for a "small" setup (less than a dozen SSH connections and a low-traffic HTTPS server), then `sslh-fork` is probably the best option for you.
- `sslh-select` uses only one thread, which monitors all connections at once. It is more recent and less tested, but the main process only incurs a 16 byte overhead per connection. However, if it stops then you will lose all non-forked connections, which means you can only upgrade it remotely if the necessary connections are set to fork mode. If you're going to use `sslh` on a "medium" setup (a few thousand SSH connections, and another few thousand SSL connections), `sslh-select` will be the most suitable option.
- `sslh-ev` is the most recent option, introduced in version 2.0. It's almost functionally identical to `sslh-select`, but uses libev to scale much higher, making it ideal if you have a very large site (tens of thousands of connections).

## See also

- Difference between sslh-fork and sslh-select
- basic.cfg
- example.cfg

Category:

- Networking

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