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48 votes
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How do I check if Log4j is installed on my server?

Try this script to get a hint: echo "checking for log4j vulnerability..." OUTPUT="$(locate log4j|grep -v log4js)" if [ "$OUTPUT" ]; then echo "[WARNING] maybe ...
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  • 2,272
26 votes

How do I check if Log4j is installed on my server?

There is no command that will surely tell you that. Some applications ship the libraries they use directly as a jar file, some will contain them in an archive. And even then you don't know which ...
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19 votes
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How do you upgrade the Ubuntu Version without upgrading the packages?

Your question indicates a misunderstanding of what the release version of Ubuntu actually means. ‘21.04’ is not some random number, it’s a guarantee that: Packages available at the time of release of ...
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18 votes

How to view all ssl certificates in a bundle?

openssl storeutl -noout -text -certs bundle.crt Paraphrasing from the OpenSSL documentation: The openssl storeutl app was added in OpenSSL 1.1.1. The storeutl command can be used to display the ...
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  • 181
12 votes
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Is this server overloaded (htop screenshots)

Your server has only two CPUs and LA (load average) in the range 10-15. That means that the running processes demand more CPU time than the CPUs can handle. You can read much more about LA in this ...
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  • 8,139
10 votes

How do I check if Log4j is installed on my server?

Try this Commands: dpkg -l | grep liblog4j dpkg -l | grep log4 find / -name log4j-core-*.jar locate log4j | grep -v log4js
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10 votes

Is this server overloaded (htop screenshots)

Define ‘overloaded’. If you’re just going by load average, then yes, it’s overloaded (by a factor of about 5-7.5). However, load average is only a reasonable metric to use if your workload is ...
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9 votes

How do you upgrade the Ubuntu Version without upgrading the packages?

No, this is not possible. If you don't update the packages, you don't have the new version.
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8 votes

Can't run docker-container 'failed to create endpoint frosty_varahamihira on network bridge'

install the linux-modules-extra-raspi package to get the veth module.
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6 votes
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Why doesn't dkim sign the letter?

It appears you have accidentally missed the section in the tutorial titled "Connect Postfix to OpenDKIM", which configures OpenDKIM on Unix domain sockets instead of the default TCP ...
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  • 2,738
6 votes
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How can I know that Ubuntu 18.04 Bionic's latest OpenSSL is really 1.1.1n?

Once a security update is in status released, the simple thing to do is apply updates, apt update && apt upgrade Consider implementing some kind of patch management report to confirm all ...
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6 votes
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Unable to run `apt update` on Ubuntu 21.10

Impish went EoL on the 14th of July. As such, its repositories can no longer be found on the mirrors, so if you want to continue using this version, you need to use old-releases.ubuntu.com as your ...
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  • 6,492
5 votes

sendmail (or postfix) is always failing with Helo command rejected

Other mail servers on the Internet generally expect your server to identify itself using its fully qualified domain name, and for the relevant forward and reverse DNS records to match. This does not ...
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5 votes

How to find out what service is listening on a specific port of a Ubuntu server without proccess id?

You're running operating system that implements Wireguard as a kernel module. Your kernel is listening on this port, and since there's no process owning that socket no PID is reported by netstat.
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  • 2,256
5 votes

How do I check if Log4j is installed on my server?

I wrote this Python script to find vulnerable Log4j2 versions on your system: https://github.com/fox-it/log4j-finder It works by by scanning the disk and inside Java Archive files recursively and ...
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  • 51
4 votes

ping: Warning: time of day goes back (-203647us), taking countermeasures

This has happened to me on AMD type processors before, where the clocksource wasn't shared between CPUs (it was set to jiffies for me). One of the CPU's was a few jiffies ahead of the other causing ...
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  • 22.9k
4 votes
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script backups sqlite database, when ran as a cron the db and names are mangled

Most likely, you're not actually running ./backup.sh when running it manually but rather bash ./backup.sh. The only POSIX compliant way to compute a value through the shell is with $(( expr )). In ...
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  • 1,978
4 votes
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Does FIN-WAIT-1 mean I was hacked?

Has someone successfully connected? Yes, but this doesn't actually mean anything; it only says a TCP connection was established and then closed. There is no relationship with what the remote user was ...
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  • 68.5k
4 votes
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Hide my password in Ansible Playbook

That's not possible. At some point you need to store something that allows you to decrypt the password. Use credentials that are generated specifically for this process, no personal credentials. ...
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4 votes

How do I check if Log4j is installed on my server?

log4jscanner Published by Google under the Apache-2.0 License, log4jscanner is a log4j vulnerability filesystem scanner and Go package for analyzing JAR files.
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  • 2,738
4 votes

How do you upgrade the Ubuntu Version without upgrading the packages?

There's no "Ubuntu version" without the packages. Actually, there is no Ubuntu without the packages. Ubuntu is just a vast collection of packages, and an Ubuntu version contains specific ...
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  • 143
4 votes

How can I know that Ubuntu 18.04 Bionic's latest OpenSSL is really 1.1.1n?

So, how would I know that this is truely 1.1.1n? it won't be 1.1.1n as, as John Mahowald says, Ubuntu will have backported the fix into their supported version for 18.04 which from the linked table ...
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  • 114k
4 votes
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High swap usage on Ubuntu server

As you can see from vmstat output you do not have si or so activities, even the average (first line) is negligible. Try to play with swappiness but if you do not see serious performance degradation ...
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  • 3,015
3 votes

scp failing with vast.ai

scp -P <port> <local file> root@<ip>:<dir> Try with a capital "-P" for the port flag.
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3 votes

Can't install mailparse on Ubuntu 20.04

It is a known bug on PECL mailparse since 2015, see #71813 Mailparse pecl install fails with php 7 #71181 Install failed : required mbstring then is enable (sic) If your distro doesn't provide ...
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  • 2,356
3 votes
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Postfix double relay configuration

ServerB will be using ServerA as the relay or relayhost, similar to how ServerA is currently using smtp.public.com as the relay. Additionally ServerA must be configured in some way to grant ...
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3 votes

Unable to ssh using ProxyJump but it works with ssh -J

The difference between your command line ssh -J ubuntu@54.170.186.144 ubuntu@10.240.0.20 and what I recommend you do to reference your configuration ssh remote is that the latter has neither IPs nor ...
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  • 6,621
3 votes
Accepted

Unable to ssh using ProxyJump but it works with ssh -J

The matching is done on Host stanza, not on HostName. Try: ssh ubuntu@remote
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  • 2,785
3 votes

Does FIN-WAIT-1 mean I was hacked?

No. It means that the socket is closed. It's a TCP State.
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  • 3,631
3 votes
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Redirect URL path to an action on index?

You definitely need to trigger the pop-up on the client side. Here's a quick sample you can easily try and adjust (and secure) to your needs: <html> <head> <script type="...
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  • 241

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