Initial working code

.gitignore

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+endlessh

Makefile

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+.POSIX:
+CC      = cc
+CFLAGS  = -std=c99 -Wall -Wextra -Wno-missing-field-initializers -Os
+LDFLAGS = -ggdb3
+LDLIBS  =
+
+endlessh: endlessh.c
+	$(CC) $(LDFLAGS) $(CFLAGS) -o $@ endlessh.c $(LDLIBS)
+
+clean:
+	rm -rf endlessh

README.md

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+# Endlessh: an SSH tarpit
+
+Endlessh is an SSH tarpit that *very* slowly sends a randomized SSH
+banner. It keeps clients locked up for hours or even days at at time.
+The idea is that you put your real SSH server on another port and let
+the script kiddies themselves stuck in this tarpit instead of bothering
+real server.
+
+Since the tarpit is in the banner before any cryptographic exchange
+occurs, this program doesn't depend on any cryptographic libraries. It's
+a simple, single-threaded, standalone C program. It uses `poll()` to
+trap multiple clients at a time.
+
+### Usage
+
+Usage information is printed with `-h`.
+
+```
+Usage: endlessh [-vh] [-d MSECS] [-m LIMIT] [-p PORT]
+  -d INT    Message millisecond delay [10000]
+  -h        Print this help message and exit
+  -m INT    Maximum number of clients [4096]
+  -p INT    Listening port [2222]
+  -v        Print diagnostics to standard output (repeatable)
+```
+
+The purpose of limiting the number of clients (`-m`) is to avoid tying
+up too many system resources with the tarpit. Clients beyond this limit
+are left in the accept queue, not rejected instantly.

UNLICENSE

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+This is free and unencumbered software released into the public domain.
+
+Anyone is free to copy, modify, publish, use, compile, sell, or
+distribute this software, either in source code form or as a compiled
+binary, for any purpose, commercial or non-commercial, and by any
+means.
+
+In jurisdictions that recognize copyright laws, the author or authors
+of this software dedicate any and all copyright interest in the
+software to the public domain. We make this dedication for the benefit
+of the public at large and to the detriment of our heirs and
+successors. We intend this dedication to be an overt act of
+relinquishment in perpetuity of all present and future rights to this
+software under copyright law.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
+IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY CLAIM, DAMAGES OR
+OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
+ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
+OTHER DEALINGS IN THE SOFTWARE.
+
+For more information, please refer to <http://unlicense.org/>