Oper Challenge and Response System $Id: challenge.txt,v 1.2 2004/02/02 23:42:53 ircd Exp $ Copyright (c) 2001 by ircd-hybrid team ---------------------------------------------------------------------- ircd-hybrid In an effort to reduce the damage caused to a network by a hacked O-line, Hybrid supports an OpenSSL based challenge-response system. This new system allows the admin to remove all oper block passwords from the conf file. Authentication is done through a public/private key. ---------------------------------------------------------------------- Requirements The ircd must be compiled with the --enable-openssl option to configure . If configure detects a working openssl library, --enable-openssl is implicitly enabled. oper {} blocks should not have normal passwords, but should contain the the name of the private key file. However it is possible for the user to use both challenge and normal passwords, but this would defeat the purpose of the challenge system. m_challenge.so must be loaded. The oper has their private key file and an implementation of the RSA Respond tool available to be run. ---------------------------------------------------------------------- Process Each oper should have a private key file and a public key file. The keys can be generated with the mkkeypair utility provided in tools/. The keys are compatible with cryptlink keys. The oper keeps their private key file in a safe place, and gives their public key file to their admin(s). The admin will place an entry for the public key file into a field called rsa_public_key_file of each oper's oper {} block in the conf file. The oper wishes to obtain their operator status, and issues the CHALLENGE command. The server will print out a long hexadecimal string, that needs to be fed to the respond utility provided in tools/rsa_respond. The respond program will generate an answer that is fed back to the CHALLENGE command. ---------------------------------------------------------------------- Generating the Key Files The keys can be generated with the openssl command as follows: openssl genrsa -des3(1) -out rsa.key 1024(2) openssl rsa -in rsa.key -pubout -out rsa.pub (1) The -des3 must be included in order to create a key with a passphrase. Omitting this option will create a non protected key. (2) The key size must be 1024 or below. The challenge sent for a longer keysize will be too long to fit into the ircd's 512 byte line constraint. It is highly recommended that you set a password on your private key. The tools/mkkeypair utility cannot be used to create a key suitable for use in CHALLENGE. ---------------------------------------------------------------------- Using CHALLENGE and respond Note: All examples assume the use of the stock respond client included with the Hybrid 7 source, run on a UNIX(c) platform. The administrator of the server you oper on should remove the password in your oper {} block and replace it with an entry for your public key, so that /oper will be disabled. Note: The public key is a VERY long string. The oper will issue /challenge oper_nick, and see something like below: *** 56F1FDAE4C590C524CF758917E62C2A2A1376CB9C4C2E7D411BB0AD9C4A 605A2D05A94E7254197E9D71438B5FB565B6FD35465E462305F35F4A2D45311 F983B3E062F635912FA155B4B1E18EAA782CC107F4C9DA83092658D16A2E88A 6BCF9820F5A044A29CDD4C062F05BF509CA3B561375CBC4179BD1CF6026BDE9 60E52C6B Note: The challenge is all on one line. Note: With some clients, the oper will have to issue /quote CHALLENGE instead of /challenge. The oper will then have to feed that challenge to the respond program. +------------------------------------------------------------------+ | The respond utility's syntax is: | | | |$ ./respond private_key_file challenge_from_server | | | | | | Example: | | | |wcampbel@botbay (rsa_respond): ./respond hwy.key \ | |56F1FDAE4C590C524CF758917E62C2A2A1376CB9C4C2E7D411BB0AD9C4A605A2D0| |5A94E7254197E9D71438B5FB565B6FD35465E462305F35F4A2D45311F983B3E062| |F635912FA155B4B1E18EAA782CC107F4C9DA83092658D16A2E88A6BCF9820F5A04| |4A29CDD4C062F05BF509CA3B561375CBC4179BD1CF6026BDE960E52C6B | |Keyphrase: | |6B882932DD00F86123869E401F7334B9B0D0018A60F1DE244E90E47246AA87C7 | | | | Note: The challenge parameter must be on one line. | +------------------------------------------------------------------+ The keyphrase must be entered properly to get the response. The bottom line is the response that must be sent back to the server. The oper will issue the following command in order to obtain operator status: /challenge +6B882932DD00F86123869E401F7334B9B0D0018A60F1DE244E90E47246AA87C7 Note: The '+' is needed If successful, the oper will obtain operator status on the server. +------------------------------------------------------------------------+ | Warning | |------------------------------------------------------------------------| | If the CHALLENGE fails, and you use ircII, EPIC, or BX, you may get | | disconnected with the client asking for the server password. This is a | | client bug, not an ircd bug. | +------------------------------------------------------------------------+ ---------------------------------------------------------------------- RSA Respond Tool The RSA Respond tool is a vital part of challenge/response system. In order to function, the operator must have must have a way to quickly issue the respond command, and to copy and paste data to and from the IRC client. The respond source code is included with the Hybrid 7 source, in the tools/rsa_respond directory. A distributable tar file can easily be created by issuing make rsa_respond in the root of the source tree. The file rsa_respond.tar.gz will be created in the root of the source tree. rsa_respond.tar.gz should compile with little or no modifications[1] on most UNIX(c) and UNIX-like platforms[2]. The README in the tar archive gives more information. A copy of the source tar file is available on http://ircd.botbay.net/pub/hybrid/rsa/rsa_respond.tar.gz. For Windows platforms, there are two available RSA Respond tools. One is a text only port of the stock tool. The binary is available from http://ircd.botbay.net/pub/hybrid/rsa/rsa_respond-bin.tar.gz. The other tool is a GUI enabled version[3]. The source tree[4] is available from http://ircd.botbay.net/pub/hybrid/rsa/winrespond-src.tar.gz. A binary distribution is available from http://ircd.botbay.net/pub/hybrid/rsa/winrespond-bin.tar.gz. With the appropriate version of the RSA Respond tool, any operator can protect their privileged access to the server, with little additional effort over using standard operator passwords. ---------------------------------------------------------------------- Benefits The greatest benefit of using the challenge/response system is that there are no passwords sent over the network in plaintext. There are also no credentials left on the server side, as only public keys are kept in the conf. The use of public/private key encryption provides far greater security over having a single password, and may (if the key is kept secure, and has a good passphrase) virtually eliminate hacked O-lines. ---------------------------------------------------------------------- A. Numerics :server 381 user :You have entered... the Twilight Zone!. :server 386 user :challenge-text :server 464 user :Password Incorrect :server 491 user :Only few of mere mortals may try to enter the twilight zone Note: The text used can be changed by the server administrator. ---------------------------------------------------------------------- B. Scripting The following script is for EPIC 4 only. It was written by Greg Prosser, xyst . Please note that passphrase protected keys cannot be used in conjunction with this script. BEGIN challenge.irc # challenge.irc -- authenticate to a hybrid-7 server with challenge response # oper authentication. --gnp (xyst) # note: this is almost gauranteed to not work if your key needs a passphrase # # credit goes to hop for pipe from the default script archive, which doesn't # work, but gave me a framework for execing stuff and getting the response. # For Hybrid's cvs... # $Id: challenge.txt,v 1.2 2004/02/02 23:42:53 ircd Exp $ xecho ... Loading challenge.irc by xyst, feer. # you might want to change these.. @challenge.path=[~/.irc/respond] @challenge.key=[~/.irc/challenge.identity] @challenge.num=0 @challenge.response=[] @challenge.savepath=[~/.irc/challenge.config] alias rsaconfig { if ([$0]) { switch ($tolower($0)) { (resppath) { if ([$1]) { @challenge.resp=[$1] xecho $G Challenge -- resppath is now: $1 } { xecho $G Challenge -- resppath: $challenge.path } } (keypath) { if ([$1]) { @challenge.key=[$1] xecho $G Challenge -- keypath is now: $1 } { xecho $G Challenge -- keypath: $challenge.key } } (save) { @unlink($challenge.savepath) @fd=open($challenge.savepath W) @write($fd @challenge.path=[$challenge.path]) @write($fd @challenge.key=[$challenge.key]) @close($fd) xecho $G Challenge -- saved settings. } (*) { xecho $G Usage: /rsaconfig [value] } } } { xecho $G Current settings for challenge.irc: rsaconfig resppath rsaconfig keypath xecho $G Type /rsaconfig to change these, /rsaconfig save saves them. } } alias challenge { if ([$0]) { ^quote challenge $0 } { xecho $G Usage: /challenge } } on ^386 * { xecho $G Got oper-challenge from server, sending response.. @challenge.num++ ^on ^exec "chall$challenge.num *" { @challenge.response=[$1] } ^exec -name chall$challenge.num $challenge.path $challenge.key $1 ^wait %chall$challenge.num ^on exec -"chall$challenge.num *" ^stack push on raw_irc ^stack push on 381 ^on ^raw_irc "$S 464 *" { xecho $G Challenge incorrect. Check your key.;^stack pop on raw_irc;^stack pop on 381 } ^on -381 * { ^stack pop on 381;^stack pop on raw_irc } ^quote challenge +$challenge.response } if ([$fexist($challenge.savepath)] > 0) { xecho $G Loading settings from $challenge.savepath .. ^load $challenge.savepath } { xecho $G Config file not found, try /rsaconfig save\; using defaults. } rsaconfig Notes [1] Some platforms may require Makefile changes in order to link in the OpenSSL library. This may change in the future. [2] Platforms known to function include: Linux, FreeBSD, Solaris, and Cygwin. [3] A screenshot of the program is available on http://kabel.pp.ru/sgml/winrespond.png . [4] The winrespond source depends on a working, up to date, Cygwin installation.