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24.05.2020

rkhunter CRLF confusion

On my Linux hosts I'm running rkhunter. On a newly configured host it lately reported the following warning:

Warning: The SSH and rkhunter configuration options should be the same:
        SSH configuration option 'PermitRootLogin': no
	Rkhunter configuration option 'ALLOW_SSH_ROOT_USER': no

On first sight the warning does not seem to make much sense, as both configuration options seem to be set to the same value (no).
But digging further reveals that they are stored slightly different:

# file /etc/rkhunter.conf
/etc/rkhunter.conf: ASCII text
# file /etc/ssh/sshd_config
/etc/ssh/sshd_config: ASCII text, with CRLF line terminators

Turns out that rkhunter is also checking the line terminators as part of the configuration values, and warns because they are different.

Knowing this, the fix is simple: run dos2unix on the CRLF file

11:22 | Linux | Permalink

21.05.2020

ipaddr CLI tool

While doing some maintenance on my server, I got tired of searching through the output of ip addr show to find the IP addresses configured on the interfaces.
Thus I wrote a simple CLI tool to display the information I needed in a concise and human friendly form: ipaddr

$ ipaddr
lo          127.0.0.1/8
ens5        198.51.100.160/24
tun24008    10.123.199.78/32
tun71991639 10.200.123.5/32
tun26724    10.100.100.235/32
tun3883710  10.123.111.7/32

A nice side-effect of writing this in Go is that it works out-of-the-box also on non-Linux systems :-)

19:38 | Networking | Permalink