Fixing Slow SSH Speeds With IPQoS


The Differentiated Services Code Point (DSCP) field in an IP header is for classifying network data and providing Quality of Service (QoS). The default SSH DSCP setting for non-interactive sessions is CS1. Within the OSL network, CS1 packets might be dropped very frequently, thus resulting in poor performance when SCPing.


The poor performance when using SCP or rsync over secure shell can be remedied by adding -o IPQoS=throughput to your scp or rsync command. Another more permanent fix would be to add this to your ssh config:

Host *