So I come to work for yet *another* company who have a 192.168.0.0/24 network on their LAN. It’s not that it’s a bad idea as such, but history had made me come to realise it can cause problems later on. How ?
Hint: most domestic vendors of home network equipment (be they switches, routers or something with ADSL built into them) tend to use either 192.168.0.0 /24, 192.168.1.0/24 or 192.168.254.0/24
Yup, if you have a home network, chances are that it and all your home devices are on ip addresses 192.168.0.something, or a 192.168.1.something, with a network mask of 255.255.255.0.
If you create a 192.168.0.0 or 192.168.1.0 network in your office environment and then try to connect to the office VPN from your home LAN, these identical networks are likely to clash. The communication kit involved cannot deal with there being x2 identical 192.168.x.x networks in x2 different locations at the same time. As result, stuff may not work correctly. For example, if I connect to th work LAN from home, once the VPN connection is established, I cannot connect to anything on my home network until I disconnect.
Admittedly I work in IT and can work around or put fixes in place. But imagine if I was a co-worker from say marketing, or sales, or, *gasp horror*, someone from senior management. I’m trying to connect to the office from home, but it not going according to the instructions you gave me because we both have a 192.168.1.0 network !
You can imagine the long and frustrating support call(s) that ensue with them trying to vaguely convey to you their setup and you gently smashing a fork into your forehead to try and keep from going insane.
The long term work around is this. If you absolutely must have /24 networks in the office (/24 is a nice size network and very easy to calculate in your head) then use anything other than 192.168. with a 255.255.255.0 network mask. What you use doesn’t matter. As long as you avoid 192.168.x.x, you will reduce the possibility of clashing with some home user LAN over a VPN connection at a later date.
