Tag Archives: ubuntu

Posts related to Ubuntu/Debian Linux

WordPress Tuning

I’ve done a little tuning to my WordPress setup. In order to keep up to date, I’ve switched from the Ubuntu installation to a downloaded installation under /opt/wordpress. This is owned by my user and served by apache running as www-data. Updates are done using the sftp add-on.

Securing /opt/wordpress

I added myself to the www-data group. This allow apache to read any files with group access, but prevents writing if the web-server is compromised.

I set the group sticky bit on all the directories. If required, setting it on the wp-content/upgrade directory should be sufficient.

SSH Key

I generated my key outside the home directory for www-data which is /var/www. The directory I chose is not one I would publish. However, ssh requires a .ssh/known_hosts file in its home directory. This was created and the appropriate security added. The key is password protected.

Outstanding Issues

There are some outstanding issues. I’ll look into these as time permits.

Native ssh

The WordPress ssh2 modules does not work on my server. I’ve found a couple of issues.

  • Passwords on the key don’t work. This is a known issue with a work-around. The initial connection appears to fail, but a second call should resolve the issue.
  • The is_dir function does not work. Returning true for paths that end in a slash (/) is a workaround. This got me as far as trying to install. This may be a result of how the path is constructed and there is a published workaround.
  • The is_file function appear to fail as WordPress reports the download contains no files. This is likely the same issue as for the is_dir function.

Theme upgrades

My modifications to the theme are getting a little old. The theme works reasonably well on mobile devices, but I would like to update to a more streamlined theme. The site statistics I have indicate a surprisingly high percentage of viewers use a mobile device.

Hostnames for eximstats Rejections

I use eximstats to report my daily email traffic. I have a fairly high rate of rejections, and wanted hostnames listed in the rejection reports.    To resolve this I developed a patch to capture the hostname related to the IP address, and add this data to the rejection reports.

The enhanced list saves me the effort of looking up IP addresses that were repeatedly addressed.   Occasionally, these are from legitimate servers that have been misconfigured.  DNS problems are often the cause. Continue reading

Providing IPv6 DNS resolver data with radvd

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 right approach for IPv6. radvd can be used to distribute both types of data.  The following article covers setup on Ubuntu and OpenWRT.  The Ubuntu (Debian) examples below should work with any distribution using/etc//radvd.conf to configure radvd. Continue reading

Setting Up BackupPC on Windows

My original intent in setting up BackupPC was to be able to backup my laptops. The mainly run Windows, and have a lot of shared files. Therefore I wanted a backup solution which 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 rsyncd as the protocol.   (I tried using Samba, but didn’t like the results with Windows Home editions.) This is done with an extremely minimal cygwin install 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. Continue reading

Setting Up BackupPC on Ubuntu

I recently started to do regular backups of all my systems using BackupPC. It uses the rsync protocol 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 less resources than other software I have used

This 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 rsyncd daemon process. Continue reading

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. Continue reading

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. Continue reading

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 have decreased the percent of spam which reaches my spam filters.   This article provides a discussion of the techniques used, and provides implementation examples.   Spambots tend to be simple programs which don’t handle slow servers very well.   Using a greylist is 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.

Continue reading

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. Continue reading

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 an 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. Continue reading