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To avoid port conflicts with services such as CUPS or IMAP vsftpd should be using portreserve for reserving respective ports on RHEL6. Typical changes required: Given a SysV service package that uses a particular port, (say, krb5_prop/tcp - 754): 1) Create a file named after the service, for example 'krb5_prop', which contains: krb5_prop/tcp 2) In the spec, install this file in /etc/portreserve, i.e., /etc/portreserve/krb5_prop 3) In the spec, add 'Requires: portreserve' to the package that provides the server. 4) In the init script, in the start() stanza, add: [ -x /sbin/portrelease ] && /sbin/portrelease krb5_prop &>/dev/null || : before starting the daemon. Some background can be found in bug 103401.
I forgot to mention that we are interested in ports withing the range 600 - 1023.
The vsftpd communicates on port 21 with the client that uses port > 1024. There are handled ports for data transfer. This mechanism is the same for TLS too. No one of that ports is in the range 600-1024. This could be done only by explicit setting in the vsftpd.conf file. I didn't find any occurrence using port in the range 600-1024 by vsftpd. Therefore I close it with the status 'netabug'.