One nagging issue I had with IPv6 was how to distribute DNS server addresses and search lists to my clients. It took a little research to find the solution. On IPv4 I had been using DHCP to do this, but DHCP didn’t seem to be the right approach for IPv6. radvd can be used to distribute both types of data. This article covers setup on Ubuntu and OpenWRT. The Ubuntu (Debian) examples below should work with any distribution using/etc/radvd.conf to configure radvd.
(more…)Tag: ubuntu
Posts related to Ubuntu/Debian Linux
Setting Up BackupPC on Windows
My original intent in setting up BackupPC was to be able to backup my laptops. They mainly run Windows and have a lot of shared files. Therefore I wanted a backup solution that handled de-duplication. BackupPC was just what I needed. I have already posted an article about Setting Up BackupPC on Ubuntu that includes setting up a server.
This article covers setting up BackupPC on Windows using
(more…)rsyncdas the protocol. (I tried using Samba, but didn’t like the results with Windows Home editions.) This is done with an extremely minimalcygwininstall available from the BackupPC site on SourceForge. The backups described here are not designed for bare metal recovery. They should include all the user’s files and some of the configuration data for installed applications.Setting Up BackupPC on Ubuntu
I recently started to do regular backups of all my systems using BackupPC. It uses the
rsyncprotocol to limit the amount of data transferred during backups. Once the initial backup is done, future backups only need to copy incremental changes. This requires far fewer resources than other software I have usedThis article covers setting up the server on Ubuntu and configuring backups for Ubuntu and OpenWRT. A future article will cover backing up Windows systems using an
(more…)rsyncddaemon process.Email Logins for Dovecot and Exim
While I was cleaning up my Ubuntu Email server configuration, I consolidated my login security. My SMTP server is Exim and my IMAP server is Dovecot. Mail User Agents (MUAs) use authentication over TLS encrypted connections to access IMAP and SMTP. Both programs had their own password configuration.
Exim includes Dovecot in its supported authentication mechanisms. This enables one authentication mechanism to be used for both SMTP and IMAP (or POP3). This post also includes configuration details for forced authentication over the Submission port.
(more…)Implementing IPv6 Part 2
We are quickly running out of IPv4 addresses. Are you ready for World IPv6 Day on June 8th, 2011? I have prepared my configuration on OpenWRT and Ubuntu. This includes configuring DNS using bind, email using Exim, and a Squid web proxy.
Having verified that I could establish IPv6 connectivity, I chose to improve my connectivity. This started with getting a tunnel from Hurricane Electric and updating my configuration. I then updated my bind server and Exim mail server support IPv6 addresses. This posting updates and continues from my post on Implementing IPv6 6to4 on OpenWRT. Review it for information on creating a tunnel and running radvd on OpenWRT.
(more…)Blocking Spam with Exim
Recent reports indicate that spam is increasing again. I have been using Exim to filter spam for several years. Some recent tuning I have done has decreased the percent of spam that reaches my spam filters. This article provides a discussion of the techniques used and provides implementation examples. Spambots tend to be simple programs that don’t handle slow servers very well. Using a greylist is an effective method of blocking them as they usually don’t retry. My latest changes use delays to cause many spambots to abandon their attempt. Greylisting is used only for poorly configured servers that make it to the Recipient command.
(more…)Transparent Squid Proxy
Over the holidays, I had a user experience and attempted browser hijacking. It appeared to have bypassed my squid proxy. My updated configuration now sends all web access via squid. The old firewall rules, that allowed direct access to the Internet, have been replaced with a transparent Squid proxy. This runs on my existing Squid Proxy using another port.
(more…)Manual networking for KVM
I found the networking configured by
libvirt(KVM) did not allow me to firewall the network as I desired. I use Shorewall for firewalling, and DNSMasq for internal DNS and DHCP. After a little experimentation, I found that I could configure Ubuntu to create the network. This allows me to get a reliable firewall configuration with a virtual DMZ.The virtual hosts are assigned to a bridge, and only have connectivity to other networks as defined in the Shorewall configuration. A single DNSMasq server provides DSN and DHCP services for all virtual servers, as well as the network the server is connected to. The network and firewall configuration remains consistent even as servers are cycled up and down. An additional bridge was created to support virtual servers in the DMZ zone.
This page has been updated in 2019 to reflect changes in the tools.
(more…)Remote Desktops with VNC and RDP
I find it useful to have a remote desktop to my Ubuntu systems. On secure connections, I have been using VNC via xinetd. Connections with xrdp where possible, but it wasn’t launching the desktop for the connection. For secure terminal connections, I stick with ssh. All these connections have a login at the start of the connection. This is how I do it.
(more…)Implementing DKIM with Exim
This article was updated in February 2014 to reflect changes in policy and reporting options. The earlier ADSP (Author Domain Signing Practices) information has been removed.
DomainKeys Identified Mail (DKIM) provides a method to confirm the origin of an e-mail. DKIM also provides some protection against tampering. Unlike SPF, this validation applies to the contents of the message when it is signed. Like SPF, the information required for validation is added to DNS.
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