base on SSH tarpit that slowly sends an endless banner # Endlessh: an SSH tarpit Endlessh is an SSH tarpit [that *very* slowly sends an endless, random SSH banner][np]. It keeps SSH clients locked up for hours or even days at a time. The purpose is to put your real SSH server on another port and then let the script kiddies get stuck in this tarpit instead of bothering a 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 [-vhs] [-d MS] [-f CONFIG] [-l LEN] [-m LIMIT] [-p PORT] -4 Bind to IPv4 only -6 Bind to IPv6 only -d INT Message millisecond delay [10000] -f Set and load config file [/etc/endlessh/config] -h Print this help message and exit -l INT Maximum banner line length (3-255) [32] -m INT Maximum number of clients [4096] -p INT Listening port [2222] -s Print diagnostics to syslog instead of standard output -v Print diagnostics (repeatable) ``` Argument order matters. The configuration file is loaded when the `-f` argument is processed, so only the options that follow will override the configuration file. By default no log messages are produced. The first `-v` enables basic logging and a second `-v` enables debugging logging (noisy). All log messages are sent to standard output by default. `-s` causes them to be sent to syslog. endlessh -v >endlessh.log 2>endlessh.err A SIGTERM signal will gracefully shut down the daemon, allowing it to write a complete, consistent log. A SIGHUP signal requests a reload of the configuration file (`-f`). A SIGUSR1 signal will print connections stats to the log. ## Sample Configuration File The configuration file has similar syntax to OpenSSH. ``` # The port on which to listen for new SSH connections. Port 2222 # The endless banner is sent one line at a time. This is the delay # in milliseconds between individual lines. Delay 10000 # The length of each line is randomized. This controls the maximum # length of each line. Shorter lines may keep clients on for longer if # they give up after a certain number of bytes. MaxLineLength 32 # Maximum number of connections to accept at a time. Connections beyond # this are not immediately rejected, but will wait in the queue. MaxClients 4096 # Set the detail level for the log. # 0 = Quiet # 1 = Standard, useful log messages # 2 = Very noisy debugging information LogLevel 0 # Set the family of the listening socket # 0 = Use IPv4 Mapped IPv6 (Both v4 and v6, default) # 4 = Use IPv4 only # 6 = Use IPv6 only BindFamily 0 ``` ## Build issues Some more esoteric systems require extra configuration when building. ### RHEL 6 / CentOS 6 This system uses a version of glibc older than 2.17 (December 2012), and `clock_gettime(2)` is still in librt. For these systems you will need to link against librt: make LDLIBS=-lrt ### Solaris / illumos These systems don't include all the necessary functionality in libc and the linker requires some extra libraries: make CC=gcc LDLIBS='-lnsl -lrt -lsocket' If you're not using GCC or Clang, also override `CFLAGS` and `LDFLAGS` to remove GCC-specific options. For example, on Solaris: make CFLAGS=-fast LDFLAGS= LDLIBS='-lnsl -lrt -lsocket' The feature test macros on these systems isn't reliable, so you may also need to use `-D__EXTENSIONS__` in `CFLAGS`. ### OpenBSD The man page needs to go into a different path for OpenBSD's `man` command: ``` diff --git a/Makefile b/Makefile index 119347a..dedf69d 100644 --- a/Makefile +++ b/Makefile @@ -14,8 +14,8 @@ endlessh: endlessh.c install: endlessh install -d $(DESTDIR)$(PREFIX)/bin install -m 755 endlessh $(DESTDIR)$(PREFIX)/bin/ - install -d $(DESTDIR)$(PREFIX)/share/man/man1 - install -m 644 endlessh.1 $(DESTDIR)$(PREFIX)/share/man/man1/ + install -d $(DESTDIR)$(PREFIX)/man/man1 + install -m 644 endlessh.1 $(DESTDIR)$(PREFIX)/man/man1/ clean: rm -rf endlessh ``` [np]: https://nullprogram.com/blog/2019/03/22/ ", Assign "at most 3 tags" to the expected json: {"id":"3681","tags":[]} "only from the tags list I provide: [{"id":77,"name":"3d"},{"id":89,"name":"agent"},{"id":17,"name":"ai"},{"id":54,"name":"algorithm"},{"id":24,"name":"api"},{"id":44,"name":"authentication"},{"id":3,"name":"aws"},{"id":27,"name":"backend"},{"id":60,"name":"benchmark"},{"id":72,"name":"best-practices"},{"id":39,"name":"bitcoin"},{"id":37,"name":"blockchain"},{"id":1,"name":"blog"},{"id":45,"name":"bundler"},{"id":58,"name":"cache"},{"id":21,"name":"chat"},{"id":49,"name":"cicd"},{"id":4,"name":"cli"},{"id":64,"name":"cloud-native"},{"id":48,"name":"cms"},{"id":61,"name":"compiler"},{"id":68,"name":"containerization"},{"id":92,"name":"crm"},{"id":34,"name":"data"},{"id":47,"name":"database"},{"id":8,"name":"declarative-gui "},{"id":9,"name":"deploy-tool"},{"id":53,"name":"desktop-app"},{"id":6,"name":"dev-exp-lib"},{"id":59,"name":"dev-tool"},{"id":13,"name":"ecommerce"},{"id":26,"name":"editor"},{"id":66,"name":"emulator"},{"id":62,"name":"filesystem"},{"id":80,"name":"finance"},{"id":15,"name":"firmware"},{"id":73,"name":"for-fun"},{"id":2,"name":"framework"},{"id":11,"name":"frontend"},{"id":22,"name":"game"},{"id":81,"name":"game-engine "},{"id":23,"name":"graphql"},{"id":84,"name":"gui"},{"id":91,"name":"http"},{"id":5,"name":"http-client"},{"id":51,"name":"iac"},{"id":30,"name":"ide"},{"id":78,"name":"iot"},{"id":40,"name":"json"},{"id":83,"name":"julian"},{"id":38,"name":"k8s"},{"id":31,"name":"language"},{"id":10,"name":"learning-resource"},{"id":33,"name":"lib"},{"id":41,"name":"linter"},{"id":28,"name":"lms"},{"id":16,"name":"logging"},{"id":76,"name":"low-code"},{"id":90,"name":"message-queue"},{"id":42,"name":"mobile-app"},{"id":18,"name":"monitoring"},{"id":36,"name":"networking"},{"id":7,"name":"node-version"},{"id":55,"name":"nosql"},{"id":57,"name":"observability"},{"id":46,"name":"orm"},{"id":52,"name":"os"},{"id":14,"name":"parser"},{"id":74,"name":"react"},{"id":82,"name":"real-time"},{"id":56,"name":"robot"},{"id":65,"name":"runtime"},{"id":32,"name":"sdk"},{"id":71,"name":"search"},{"id":63,"name":"secrets"},{"id":25,"name":"security"},{"id":85,"name":"server"},{"id":86,"name":"serverless"},{"id":70,"name":"storage"},{"id":75,"name":"system-design"},{"id":79,"name":"terminal"},{"id":29,"name":"testing"},{"id":12,"name":"ui"},{"id":50,"name":"ux"},{"id":88,"name":"video"},{"id":20,"name":"web-app"},{"id":35,"name":"web-server"},{"id":43,"name":"webassembly"},{"id":69,"name":"workflow"},{"id":87,"name":"yaml"}]" returns me the "expected json"