Identifying intrusions in computer networks is important to be able to protect the network. The network is the entry point that attackers use in an attempt to gain access to valuable information from a company or organization or to simply destroy digital property. There exist many good methods already but there is always room for improvement. This thesis proposes to use reservoir computing as a feature extractor on network traffic data as a time series to train machine learning models for anomaly detection. The models used in this thesis are neural network, support vector machine, and linear discriminant analysis. The performance is measured in terms of detection rate, false alarm rate, and overall accuracy of the identification of attacks in the test data. The results show that the neural network generally improved with the use of a reservoir network. Support vector machine wasn't hugely affected by the reservoir. Linear discriminant analysis always got worse performance. Overall, the time aspect of the reservoir didn't have a huge effect. The performance of my experiments is inferior to those of previous works, but it might perform better if a separate feature selection or extraction is done first. Extracting a sequence to a single vector and determining if it contained any attacks worked very well when the sequences contained several attacks, otherwise not so well.