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85 lines
3.4 KiB
85 lines
3.4 KiB
## gosher -- A simple Gopher server in a POSIX shell script
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`gosher` is a Gopher server in a POSIX shell script. It requires only a
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standard `netcat(1)`.
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You start the server using:
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$ ./gosher [<GOPHERDIR> [<HOSTNAME> [<PORT>]]]
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If HOSTNAME is not provided, it will be set to "localhost". If PORT is
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not specified, it will bind on port 70. If GOPHERDIR is not provided, it
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defaults to "./". Before starting `gosher` you might need to modify the
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values of the variables `NETCAT` and `STYLE` in `gosher` (see "Which
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netcat?" below).
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If the selector is a directory, `gosher` will look for a file named
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`gophermap` to render the submenu. If a `gophermap` does not exist,
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`gosher` looks for the index.gph gopherfile in the folder and, if it
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exists, renders it as a gophermap. If the required selector has a '.gph'
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extension, `gosher` will treat it as a gopherfile, and render it as a
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gophermap.
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## Which netcat?
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There are currently several different implementations of `netcat(1)`,
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and each of them works in a slightly different way and/or offers a
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different set of options. For the sake of using `gosher`, the main issue
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is whether your `netcat(1)` implementation does exit or not when its
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standard input gets closed. Notably, the original `netcat(1)`
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implementation by hobbit@avian.org does **not** exit, while other common
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implementations (OpenBSD `netcat(1)`, `ncat(1)` from the nmap project,
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and GNU `netcat(1)`) normally do. The current version of `gosher` can
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work with different implementations of `netcat(1)`, provided that the
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variable `NETCAT` points to the `netcat(1)` version you want to use, and
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that the variable `STYLE` in `gosher` is set correctly. In particular,
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`STYLE` can pe set equal to either 'pipe' or 'fork'. Please check below
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what is the recommended combination for your version of `netcat(1)`:
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+----------------+--------------+--------------+
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| netcat version | STYLE='fork' | STYLE='pipe' |
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+----------------+--------------+--------------+
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| traditional | YES | NO |
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+----------------+--------------+--------------+
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| OpenBSD | NO | YES |
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+----------------+--------------+--------------+
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| ncat | YES | YES |
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+----------------+--------------+--------------+
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**N.B.: Using STYLE='pipe' is preferable, since the '-c' option used by
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the 'fork' mode is a potential security risk**
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## Running `gosher` under `chroot(8)`
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In general, it makes sense to run a server in a `chroot(8)` environment, to
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reduce the risks connected with remote exploits. If you would like to
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run `gosher` under `chroot(8)` be sure to have the following binaries (and
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the corresponding libs) available in the chroot-ed environment:
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```
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basename(1) cat(1) cut(1) date(1) dirname(1) mkfifo(1) netcat(1)
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realpath(1) rm(1) sed(1) sh(1) which(1)
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```
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Obviously, `netcat(1)` will be your preferred `netcat(1)` implementation.
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## Why `gosher`?
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Just for fun. There are only a few TCP/IP application protocols left
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that can be implemented in a few dozen lines of POSIX shell script, and
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Gopher (RFC 1436) is one of those.
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## Why calling it `gosher`?
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Well, `gosher` is just `gopher` where the `p` is replaced with an `s`,
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and `sh(1)` is all that you need to run `gosher` (if we leave
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`netcat(1)` out...).
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Also, `gopher` is probably one of the few `kosher` protocols out there.
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According to the Urban Dictionary, `gosher` is "an insult that can mean
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anything", so choose your own.
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