SIP ALG can be both useful and a pain. This can become apparent when trying to setup a SIP connection to a PBX on the internet somewhere. Or alternatively, dialling into a local PBX from externally. Many do no realise that SIP ALG is enabled by default on most routers. Read more…
As we have exhausted all IPv4 addresses it was decided to implement NAT in a lot of areas of the internet. You are probably reading this sat behind a router that is performing a variation of NAT. NAT’s purpose is to translate addresses. The main example of this would be Read more…
Many companies will have internal servers that need to be accessed outside of the organisation. These could be web servers or mail servers. Here I will show how to configure a Cisco router to map your internal servers to an external IP provided by your ISP using Network Address Translation Read more…