On Mon, 2005-10-24 at 08:40, Kai Schaetzl wrote: > I made a yum update to 4.2 yesterday. The first "major" update I did on > CentOS, I'm only using it for a few weeks now, starting with 4.1. Mainly > for evaluation for a prospected migration from Suse to CentOS. Basically > the update went very well, fast (only 180 MB needed to be installed) and > smooth. But there were two small issues where I don't know why they > happened: > 2. sshd seems to start twice or so since that update. No problems with > ssh, though. > > from boot.log: > Oct 24 14:00:16 nx05 sshd: succeeded > > from warn log: > Oct 24 14:00:16 nx05 sshd[1737]: error: Bind to port 22 on 0.0.0.0 failed: > Address already in use. > > Same thing happens when I restart sshd and even when I reload it. > There was a new sshd_config installed, I think I read something about > removing ssh 1 protocol from it. This can't be the cause. There's only one > instance of sshd running apart from the children for actual logins. > Why is this happening, how to fix it? > Most of the times I have seen this it is caused due to having IPv6 enabled. ssh binds to the port on IPv4 address or IPv6 then tries to bind a second time to the same port. Personally I usually disable IPv6 and the zero conf stuff on systems. Have not had a use for either of these on systems and I suspect the zero conf stuff could lead to security issues if/when someone studies it a little more. :) > There is another question that arises in this context: will a yum update > always overwrite with new configuration files, if that file got changed > from the originally installed one? I'm used from Suse that new > configuration files get saved with another extension if the original file > got changed or in some cases it overwrites the file but copies the old > file to a backup. I can also expressly exclude some config files from > overwriting via sysconfig (if I remember correctly), can I do similar with > CentOS? Many rpm packages will typically not over write configuration files that have been modified. They will create a .rpmnew file for the config file. But don't count on that action. Backups are good to have of any configuration files you have changed.