If you are on dynamic IP how do you know what the previous user of the IP was up to? You may get attacked because of that. At least with a fixed IP you know the history. My opinion is that a dynamic IP gives a false sense of security.

The main reason I paid PlusNet £5 for a static IP address was to use the BQM to monitor my internet quality and latency - the benefit more than outweighs any increased security risk for me.

I have a number of static IPs, and a number of dynamic IPs. I have a quality firewall, and log port probes and exploit attempts. There is no difference between the static and dynamic addresses - both are targeted.
Get a good router/firewall, close all unnecessary ports, and use OpenDNS or similar that allow you to block accidental accesses to known bad sites.
Assuming a dynamic IP address is safer is no better than wearing a tin-foil hat.

In reply to a post by sheephouse:

I have a number of static IPs, and a number of dynamic IPs. I have a quality firewall, and log port probes and exploit attempts. There is no difference between the static and dynamic addresses - both are targeted.

What can open a static IP address to more attacks is if it's known to be hosting publicly visible services such as email and web servers. Once a service has been identified at a particular IP address, service specific attacks will be launched against that service. That's why it's good practice to implement an intrusion prevention system on servers running these services.

A frequently changing dynamic IP address hosting externally visible services and which uses a dynamic DNS service can also be subject to increased attack if the dynamic DNS hostname is known to the attacker.

In reply to a post by sheephouse:

I have a number of static IPs, and a number of dynamic IPs. I have a quality firewall, and log port probes and exploit attempts. There is no difference between the static and dynamic addresses - both are targeted.
Get a good router/firewall, close all unnecessary ports, and use OpenDNS or similar that allow you to block accidental accesses to known bad sites.
Assuming a dynamic IP address is safer is no better than wearing a tin-foil hat.

In fact dynamic IP addresses are more prone to problems as the person who had it last could have been infected with malware, a spammer, or otherwise under attack for some reason. Which means you will find yourself randomly blocked from some services or suffering a DoS.

With a static IP address you can build a level of trust in that IP address so that you never suffer these issues or can request reevaluation if you do.

So ultimately I would argue the benefits of a static IP far outweigh the drawbacks.

Dynamic IPs aren't always so "dynamic". I've been with Virgin since 2012, with a dynamic IP that has changed ONCE in that 6 year period, even after periods of the router being turned off, or faults that caused/required disconnections. If your connection is stable, don't take it on gospel that your IP will change every time you personally disconnect/reconnect or if a fault or other action causes a disconnection/reconnection of your broadband.

In reply to a post by brookheather:

The main reason I paid PlusNet £5 for a static IP address was to use the BQM to monitor my internet quality and latency - the benefit more than outweighs any increased security risk for me.

For those in a similar position, the BQM has supported hostnames for a while now so a dynamic IP with a dynamic DNS service would mean paying for a static from any provider shouldn't really be needed any longer [for BQM].

Matt