Tag Archives: Firewall

Ipcop in VMware

I recently installed an IPcop 1.4 in vmware to replace my old firewall at home. I also need to filter some unwanted website for my kids.

=== Time/Clock problem ===
Due to the well known time sync problem of all virtual machine, the clock in my Ipcop often running slow. IPcop use fcrontab, so I add the line below to sync to NTP every 1 minute.

fcrontab -e

#Sync NTP every 1 minute
@ 1 /usr/bin/ntpdate -s pool.ntp.org

=== VPN MTU problem ===

After setting up Ipsec VPN to my office, I found that my Outlook is not able to receive emails (while the VPN is perfectly connected)

After spending hours to search and try. I found the solution is to set the VPN MTU to 1410 (in the VPN screen of IPcop). This is probably because I have a PPPoE connection.

To find out the correct MTU size, use

ping server-at-the-other-end -l 1410

where the parameter -l is to used to test the size of the packet of the the VPN, start from 1500 first, and then reduce it to find out the largest possible packet size.

Install NoMachine NX Server on CentOS 5

NX is a quick way to remote administrate my Linux servers (speed comparable to RDP or ARD).

The NoMachine NX Free Edition only allow 2 concurrent sessions (enough for administration purpose). If you need more concurrent sessions, you have to use the paid version or FreeNX server.

Software Used


  • CentOS 5.2 i386
  • NoMachine NX Free Edition for Linux 3.2.0-16


  • Windows Vista Business SP1
  • NoMachine NX Client for Windows 3.2.0-13

Install NX Server

  • login as root
  • startx
  • go to www.nomachine.com
  • Download the NX Free Edition for Linux i386 Client, Node and Server
  • double-click nxclient-3.*.i386.rpm to install the client
  • double-click nxnode-3.*.i386.rpm to install the node
  • double-click nxserver-3.*.i386.rpm to install the server

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Install CentOS 5 in VMware

Software Used:

  • Windows 2003 R2 SP2 x64 Standard Edtion (as host)
  • VMware Server 1.0.6 (free) Edition
  • Get CentOS-5.2-i386-netinstall.iso from www.centos.org mirror

Create the virtual machine

  • Choose Redhat Enterprise 4 as the OS
  • Memory (at least 128MB absolute minimum, at least 384MB for GUI installation)
  • Remove the USB, Sound, etc (optional)
  • Boot into VM BIOS, remove Serial, Parallel, etc. (optional)
  • Disable Snapshots
  • Startup as Local System account
  • Ethernet: Bridged

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