From 75d2c0b49f6e41d7a908dc7d254a5f60a127d437 Mon Sep 17 00:00:00 2001 From: Stefan Kangas Date: Tue, 8 Feb 2011 12:17:00 +0100 Subject: Even more improvements to the tunnel documentation --- fripost-docs.org | 76 ++++++++++++++++++++++++++++++-------------------------- 1 file changed, 41 insertions(+), 35 deletions(-) (limited to 'fripost-docs.org') diff --git a/fripost-docs.org b/fripost-docs.org index 17d0542..89250d5 100644 --- a/fripost-docs.org +++ b/fripost-docs.org @@ -1,7 +1,7 @@ # -*- mode: org-mode; truncate-lines: nil -*- #+TITLE: Systems documentation -#+AUTHOR: The Free E-mail Association -#+DESCRIPTION: Systems documentation for The Free E-mail Association +#+AUTHOR: Fripost -- the Free E-mail Association +#+DESCRIPTION: Systems documentation for Fripost, the Free E-mail Association #+KEYWORDS: #+LANGUAGE: en #+OPTIONS: H:3 num:t toc:t \n:nil @:t ::t |:t ^:t -:t f:t *:t <:t @@ -21,8 +21,8 @@ Foundation; with no Invariant Sections, no Front-Cover Texts and no Back-Cover Texts. A copy of the license is included in a separate file called "COPYING". -This is documentation of the server configuration used by the free e-mail -association, given here in general interest of transparency. +This is the documentation of the server configuration used by the free e-mail +association, given here to provide a transparent system. Debian GNU/Linux lenny is the target system. @@ -224,16 +224,24 @@ Aptitude 3. Create a script on the backup computer to automatically backup 4. Add script to crontab - ** Configuring the e-mail servers - We will be using one main mail storage server, accessible by users via IMAP. - This server should be referred to as the main `IMAP server'. We will have two - or more mail gateways that will relay e-mail to the main server over secure - connections. These are called `smarthosts'. +*** Introduction +**** Overview + + We will be using one main mail storage server, accessible by users via IMAP. + This server should be referred to as the main `IMAP server'. We will have two + or more mail gateways that will relay e-mail to the main server over secure + connections. These are called `smarthosts'. + + The main server will also be responsible for keeping all users in an MySQL + database that will be replicated using MySQL. - The main server will also be responsible for keeping all users in an MySQL - database that will be replicated using MySQL. +**** Definitions + +IMAP server = the main storage server + +smarthost = the server receiving email from the internet (configured as MX) *** Configuring an SSH tunnel between two hosts @@ -249,52 +257,50 @@ Aptitude DEST_PORT="25" ORIGIN_PORT="1917" -**** Preparing the destination host - - 1a. Install necessary software on the destination host: - - sudo aptitude install netcat-openbsd - - 1b. Create a new user on the destination host: - - sudo adduser --home=$TUNNEL_HOME --shell=`type rbash` $TUNNEL_USER - echo "exit" | sudo -u $TUNNEL_USER tee $TUNNEL_HOME/.bash_profile - sudo passwd -d $TUNNEL_USER +**** Prepare origin - Note: We need bash, so we can not change the shell to something else. + 1. Create a key on the originating host: - (Also, make sure to add this user to AllowedUsers in /etc/ssh/sshd_config) + sudo ssh-keygen -N "" -b 4096 -f /root/.ssh/$TUNNEL_KEY + sudo cat /root/.ssh/$TUNNEL_KEY.pub -**** Preparing the originating server +**** Prepare destination - 1c. Install necessary software on the originating server: + 2a. Install necessary software on the destination host: - sudo aptitude install openbsd-inetd + sudo aptitude install netcat-openbsd - Comment: We use inetd instead of ssh -L because, among other things, ssh - -L tends to hang. + 2b. Create a new user on the destination host: -**** Steps to set up a new tunnel + sudo adduser --home=$TUNNEL_HOME --shell=`type rbash|cut -d' ' -f3` \ + --disabled-password $TUNNEL_USER + echo "exit" | sudo -u $TUNNEL_USER tee $TUNNEL_HOME/.bash_profile - 2. Create a key on the originating host: + # Also, make sure to add this user to AllowUsers in /etc/ssh/sshd_config. - sudo ssh-keygen -N "" -b 4096 -f /root/.ssh/$TUNNEL_KEY - sudo cat /root/.ssh/$TUNNEL_KEY.pub + # Note: We need bash, so we can not change the shell to something else. - 3. Add this key to the user `smtptunnel' on the destination: + 2c. Add the public key from above to this user: - THEPUBLICKEY="ssh-rsa xxxxxxxxxxx" + THE_PUBLIC_KEY="ssh-rsa xxxxxxxxxxx" sudo -u $TUNNEL_USER mkdir $TUNNEL_HOME/.ssh echo "command=\"nc localhost $DEST_PORT\",no-X11-forwarding,no-agent-forwarding,\ no-port-forwarding $THE_PUBLIC_KEY" | sudo -u $TUNNEL_USER tee $TUNNEL_HOME/.ssh/authorized_keys2 +**** Set up the tunnel + 4. Test the key on the originating host: sudo ssh -v -l $TUNNEL_USER -i /root/.ssh/$TUNNEL_KEY destination.example.com 5. Configure openbsd-inetd on the originating host: + # Comment: We use inetd instead of ssh -L because, among other things, ssh + # -L tends to hang. + + sudo aptitude install openbsd-inetd + - /etc/inetd.conf :HIDDEN: 127.0.0.1:$ORIGIN_PORT stream tcp nowait root /usr/bin/ssh -q -T -i /root/.ssh/tunnel_key smtptunnel@example.com -- cgit v1.2.3