I have written papers on the topic of network security. Now I am trying to find a place to publish one of them. Is there a list of publications by topic, somewhere? If I come across such a list, how can I determine the reputation of the various publications?
On top of the other answers, which are valid, I can add the following.
First, ask your colleagues/supervisor/boss. Senior people know the field better than you.
Then, there are some tools to automatise the process of finding journals.
There is the plain old directory-based search offered by journalseek. With that tool, you look for your discipline and see what are the journals registered there.
There are also new fascinating tools, where you can input your paper title and/or keywords and/or abtract. The tools will look for similar papers in other journals and return the journal names for you (with a similarity index).
Some publishers offer similar tools for their journals only. For example, Elsevier offers a journal finder, which works quite well. Springer offers a similar service, although it is hidden in its editing services.
I am by no way saying that those tools are the definitive way to find the perfect journal for your article. However, they enable the discovery of new journals, which is always good.
When you find a journal that seems to be suitable for you, read some of the published articles in order to grasp the quality of the journal.