Cache seems to be a must component for company with large amount of clients connected to the gateway and all of them are always online. Today, I have to install Squid as a transparent cache proxy on Ubuntu Dapper using Iptables.

Since this host is also the internet gateway, I assume that your host are currently the same thing and I will just describe the additional steps to setup a transparent proxy.

A few days ago, I had to connect to wireless network with WEP. It's my first time for WEP on Ubuntu. At the first glance, NetworkManager seemed to work because it known about the security and key. However, it didn't simply like that. In this situation, I have a key in ASCII format and I entered that key into NetworkManager with no luck. So I have to set it manually.

Once upon a time, there was a TCP/IP stack and hackers. One of the most popular attacks against TCP/IP stack is TCP SYN flood. It is not just the problem of implementation but also the TCP/IP stack itself. If you have servers in the wild, you must harden those servers.

VMware Server is totally free. All you need is just to register your name and address to obtain a number of serial numbers. You may get up to 100 serial numbers at a time. In VMware, there are 3 network types: bridge, nat, and host-only. Bridge is the most powerful one but you need an extra IP address. If you don't have one, you might be interesting in nat or host-only. Nat seems to be better to keep your guest OS up-to-date and connected to the internet. However, Nat means you can't connect to the guest OS directly from internet so you can't run it as a server. Anyway, it is possible to forward port to the guest OS behind VMware's nat.

Teapop: another POP3 daemon for Virtualmin

I have just upgraded Virtualmin and Webmin on Red Hat 8.0 to Ubuntu 6.06.1 Dapper. Everything seems to work as expect except only POP3. The old configuration on Red Hat 8.0 is to use UW ipopd. Anyway, it is the most classic one so I decided to try another approaches as follows.

If you are behind a router aka ADSL router and you are assigned a private IP address, e.g., 192.168.0.0/16, 172.16.0.0/16, or 10.0.0.0/8, you will be able to use most of Internet applications like Web, E-mail, FTP, and more. However, P2P softwares might not work well because your computer can't receive incoming connection directly. You have to choice, DMZ or Port Forwarding. In case of your router is purely hardward, PortForward.com might help. Otherwise, your router might be handmade Linux router or you are using a kind of a VPN. The most common software in Linux router or VPN is iptables. This article is to describe how to set port forwarding through DNAT using iptables.