SSH, even LISH, refusing to respond
Seeking troubleshooting guidance from the Linode community. I have a CentOS 7 Linode that I have never had any trouble accessing with PuTTY (root with key-pair access only). But today I get a blank window, and after about 20 seconds a popup says, "Network error: Connection timed out." I tried to follow this guide - ping 139.162.99.170 works fine, but telnet 139.162.99.170 22 returns:
Trying 139.162.99.170…
Connected to 139.162.99.170.
Escape character is '^]'.
SSH-2.0-OpenSSH_7.4
…(then a couple minutes later)
Connection closed by foreign host.
I then tried the Lish Console - the first time I launched it, it showed about a dozen lines of stuff that resembled some sort of log output, with the last line saying something about being out of memory and killing a process related to MySQL, but no shell prompt. I started writing this post and then flipped back to the Lish window intending to copy the output, but it had refreshed and was only showing a never-ending spinner. I have both Webmin and Monit, and neither are complaining about anything on the server (and memory usage is reasonable - RAM at about half). I used Webmin to stop and restart the SSH server, but that didn't help. Any suggestions?
2 Replies
CassandraD
Linode Staff
It's possible that there is an issue with your monitor and the system is using more memory than is being reported. If you're seeing an error about OOMing, I'd recommend starting by rebooting your server, which can sometimes temporarily bring memory usage down enough to log back in and work on troubleshooting. Here are some resources to help with that.
If rebooting doesn't seem to resolve the issue, we also have some guides to help with troubleshooting networking and SSH.
Finally, you may have some options for trying to log on with LISH by booting into Rescue Mode, which you can read about in this Community Site post.
If you'd like us to investigate and confirm there are no issues on our side, please feel free to open a Support Ticket.
Oh, I didn't notice that there had been a reply. (Apparently I don't get notification emails from this forum.) In the last day something changed to where I can log in now. Thanks for your answer, though.
When I get some time, I'll take a look at the links you shared to see if there is a memory issue I need to sort out for the future. I have had this Linode for years without running into this problem before, but I don't SSH in very frequently, so perhaps it has had OOMs that got well on their own unnoticed. What I do know is that my web/database code has run fine the whole time (including during the two days I couldn't SSH), so if there is a memory problem, it doesn't seem to be affecting the web server or related services.