SSH "login" every few seconds on storage server from backup server

heeeresjohnny

12/15/23, 8:21 AM

I recently inherited a server rack from my predecessor and am currently going through the logs and docs to see what is what in the stack.

While checking the logs of the main storage server, I noticed that there are SSH logins every few seconds in the form of:

server1 sshd[pid]: Accepted publickey for root from ip-of-second-server port 50xxx ...

and a little later:

server1 sshd[same-pid]: Received disconnect from ip-of-second-server port 50xxx:11: disconnected by user

with the second server being the backup storage server. These messages flood the logs every few seconds since the beginning of logging.

I suppose, the backup server is syncing with the main server, right? But is it normal that this happens a) via SSH and b) every few seconds ??

The filesystem on both servers is ZFS, if that is relevant.

Thanks in advance for every answer!

1 + 2

ssh

storage-server

Nikita Kipriyanov

12/15/23, 8:52 AM

Try to connect to the source of those connections and check. It looks very much like ZFS snapshot send/receive over SSH, in which case it could be normal that it is invoked every few seconds (the delay between syncs being the recovery point objective).

heeeresjohnny

12/23/23, 1:31 PM

Hey, thanks for the quick answer! Sadly, I only got it today because I wen on holidays. ;) That was indeed the case: The second server is just syncing via SSH for the snapshots

Score:1

Server

proxx

12/15/23, 10:52 AM

My first guess would be that there is a cron job running Rsync on the other machine, thus syncing 2 locations. Likely under root (crontab -e) on the other box.

Another possibility is some device using SFTP and pulling or pushing data every x interval.

+ 2

heeeresjohnny

12/23/23, 1:33 PM

Thanks for your answer! I did manage to find out what is happening between the servers and there is simply syncing of ZFS snapshots between the two via SSH. :)

proxx

12/23/23, 5:01 PM

Perfect, good to hear!

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