Slow SSH

Changing the default port on SSH can make the job of a script kiddie a bit harder but it may bring some problems for other services working on the same port, that’s what happened to me not long ago. In case you have no idea VSFTP runs on the same port as SSH, after changing the default port to 2020 I began to notice that VSFTP transters drop from 80kbps down to 20kbps after checking the VSFTPD configuration (/etc/vsftpd.conf) I found the following problem.

# Make sure PORT transfer connections originate from port 20 (ftp-data). connect_from_port_20=YES

change to

connect_from_port_20=NO

I guess that VSFTP was only trying to verify that port 20 was being used for transfers, the solution was to change the “YES” to “NO”, after restarting VSFTP the rate of the file transfers went up.

ssh — Dec 27, 2007