If you try to add an ubuntu PPA using add-apt-repository, e.g.:

sudo add-apt-repository ppa:webupd8team/java

And you get the following error:

[...]  
gpg: keyring `/tmp/tmpG9Z_HY/secring.gpg' created  
gpg: keyring `/tmp/tmpG9Z_HY/pubring.gpg' created  
gpg: requesting key EEA14886 from hkp server keyserver.ubuntu.com  
?: **keyserver.ubuntu.com: Connection refused**  
gpgkeys: HTTP fetch error 7: couldn't connect: Connection refused  
gpg: no valid OpenPGP data found.  
gpg: Total number processed: 0  
recv failed

As you may have noticed, a rather serious Ubuntu privilege escalation exploit has been disclosed today:

CVE-2015-1328: incorrect permission checks in overlayfs, ubuntu local root

The overlayfs filesystem does not correctly check file permissions when creating new files in the upper filesystem directory. This can be exploited by an unprivileged process in kernels with CONFIG_USER_NS=y and where overlayfs has the FS_USERNS_MOUNT flag, which allows the mounting of overlayfs inside unprivileged mount namespaces. This is the default configuration of Ubuntu 12.04, 14.04, 14.10, and 15.04 [1].

Introduction

In this post we will be looking at how to self-host git using gitolite.