Difference between revisions of "FAQ:Linux"

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(figlet to create ASCII test: Add update-motd.d example)
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Here is a command to install all the small tools that are quite useful
Here is a command to install all the small tools that are quite useful
apt install vim screen zsh htop iftop iotop subversion git ndisc6 debian-goodies sipcalc pwgen lshw apt-file sudo lvm2 apticron vlan dnsutils whois ldap-utils apt-transport-https xfsprogs rsync
apt install vim screen zsh htop iftop iotop subversion git ndisc6 debian-goodies sipcalc pwgen lshw apt-file sudo lvm2 apticron vlan dnsutils whois ldap-utils apt-transport-https xfsprogs rsync figlet
= Network =
= Network =
Line 443: Line 444:
cf https://wiki.mozilla.org/Thunderbird:Autoconfiguration
cf https://wiki.mozilla.org/Thunderbird:Autoconfiguration
= Others =
== figlet to create ASCII test ==
<source lang="bash">
(SSH):marc@cloud:[~]$ figlet cloud
_ _
___| | ___ _ _ __| |
/ __| |/ _ \| | | |/ _` |
| (__| | (_) | |_| | (_| |
\___|_|\___/ \__,_|\__,_|
''Example of usage''
<source lang="bash">
root@cloud:[/etc/update-motd.d]# cat /etc/update-motd.d/10-logo
# Display the hostname with a fancy ASCII mode
figlet -w 120 -t `hostname -f``

Latest revision as of 22:21, 2 December 2019


Install all my basic useful tools

Here is a command to install all the small tools that are quite useful

apt install vim screen zsh htop iftop iotop subversion git ndisc6 debian-goodies sipcalc pwgen lshw apt-file sudo lvm2 apticron vlan dnsutils whois ldap-utils apt-transport-https xfsprogs rsync figlet


Setup IPv6

Install the dibbler client

apt install dibbler-client

Update the client-duid with the one gaven for IPv6 by your provider

root@cloud:[~]# cat /var/lib/dibbler/client-duid

Edit your /etc/dibbler/client.conf

# Defaults for dibbler-client.
# installed at /etc/dibbler/client.conf by the maintainer scripts
# DDUID is stored in /var/lib/dibbler/client-duid

# 8 (Debug) is most verbose. 7 (Info) is usually the best option
#log-level 7

# To perform stateless (i.e. options only) configuration, uncomment
# this line below and remove any "ia" keywords from interface definitions
# stateless

auth-protocol reconfigure-key
auth-replay monotonic
auth-methods digest-hmac-md5
duid-type duid-ll
log-level 8

iface eth0 {
# ask for address

Update /etc/network/interfaces with the address to use

iface eth0 inet6 static
         address 2001:bc8:1234:1234::1234
         netmask 64
         accept_ra 2

nftables Firewall : Now use nftables instead of (ip|ip6|arp|eb)tables

Enable nft autocompletion in ZSH !!

  • Problem: At this time, zsh 5.7.1-1 doesn't include the _nftables completion script for nftables !!
  • Solution: Manually enable it with the command below
cd /usr/share/zsh/functions/Completion/Linux
wget https://raw.githubusercontent.com/zsh-users/zsh-completions/master/src/_nftables

List all rules

root@cloud:[~]# nft list ruleset
table inet filter {
        chain input {
                type filter hook input priority 0; policy drop;
                iif "lo" accept
                ct state established,related accept
                ct state invalid drop
                ip6 saddr fe80::/10 udp dport dhcpv6-client counter packets 26 bytes 3484 accept
                ip6 saddr fe80::/10 tcp dport dhcpv6-client counter packets 0 bytes 0 accept
                ip6 nexthdr ipv6-icmp accept
                ip6 nexthdr ipv6-icmp icmpv6 type { destination-unreachable, packet-too-big, time-exceeded, parameter-problem, mld-listener-query, mld-listener-report, mld-listener-done, nd-router-solicit, nd-router-advert, nd-neighbor-solicit, nd-neighbor-advert, ind-neighbor-solicit, ind-neighbor-advert, mld2-listener-report } accept
                ip protocol icmp icmp type { destination-unreachable, echo-request, router-advertisement, router-solicitation, time-exceeded, parameter-problem } accept
                tcp dport { ssh, http, https } ct state new accept

        chain forward {
                type filter hook forward priority 0; policy accept;

        chain output {
                type filter hook output priority 0; policy accept;

List all sets

root@cloud:~# nft add set inet filter blackhole {type ipv4_addr \; }

root@cloud:~# nft add element inet filter blackhole {,}

root@cloud:~# nft list set inet filter blackhole
table inet filter {
        set blackhole {
                type ipv4_addr
                elements = {, }



apt install mysql-server mysql-client


Install Collabora Online

Please follow https://www.collaboraoffice.com/code/linux-packages/


apt install bind9

Enable DNSSEC for a domain

https://kb.isc.org/docs/aa-00626 https://linux.die.net/man/1/dig https://www.isc.org/downloads/bind/dnssec/ https://ftp.isc.org/isc/dnssec-guide/dnssec-guide.pdf http://www.average.org/dnssec/dnssec-configuring-auto-signed-dynamic-zones.txt

  • Generate RSA keys to sign the Zone and RRs. Allow bind to read the private key to automatically sign
root@link:[~]# cd /etc/bind/keys
root@link:[/etc/../keys]# dnssec-keygen -K /etc/bind/keys leurent.eu
Generating key pair...+++++ ................................................................................................................+++++ 
root@link:[/etc/../keys]# dnssec-keygen -f KSK -K /etc/bind/keys leurent.eu
Generating key pair....+++++ .....................+++++ 
root@link:[/etc/../keys]# chmod g+r /etc/bind/keys/Kleurent.eu.*.private
  • Update your /etc/bind/named.conf.local zone
zone "leurent.eu" {
            # look for dnssec keys here:
            key-directory "/etc/bind/keys";

            # publish and activate dnssec keys:
            auto-dnssec maintain;

            # use inline signing:
            inline-signing yes;
  • Reload bind9
root@link:[~]# systemctl reload bind9.service                                                                                                23:22 Wed 27/02/2019
  • Once reloaded you should see an additional .signed version of the zone that will be automatically maintained
root@link:[/etc/../leurent]# ll
total 36K
-rw-r--r-- 1 bind bind  515 Apr 11  2017 7.e.7.3.8.c.b.
-rw-r--r-- 1 bind bind 2.0K Feb 27 23:03 leurent.eu.db
-rw-r--r-- 1 bind bind  512 Feb 27 23:08 leurent.eu.db.jbk
-rw-r--r-- 1 bind bind  19K Feb 27 23:22 leurent.eu.db.signed
-rw-r--r-- 1 bind bind 1.8K Feb 27 23:08 leurent.eu.db.signed.jnl
  • Add the public key of your 257 (KSK) and 256 (ZSK)
  • Verify the the DS and DNSKEY are visible
MBP-de-Marc:~ marc$ dig +dnssec +short DS leurent.eu @ 
65487 5 2 92937B171A4B9156CC812C1ECD74973AD48DF03A4733FD6E401C28B9 61A8F27A
36097 5 2 85619198D6D6EEFE608F59ADC3D3EFECF86452CE1667460B800334B0 B7BEFFC4
DS 8 2 86400 20190306222103 20190227212103 27363 eu. mBn1LoJ/OcNwgLpOYhpG9fkjZPtDfUPcc4ub+JdI0891/vJ1TcbEU6NU nQJ1poXJwps6L7j9gxLqiDR8+mTiSTgCH5JGHPn4wAWU4JEyhlrT3t+t CeFS8voKo70czMY0+LorM7/AnqV68DqLsxkpYlT4t3coQpkgpdEuI2Ev tZ8=

MBP-de-Marc:~ marc$ dig +dnssec +short DNSKEY leurent.eu @ 
257 3 5 AwEAAbKf831QWrZcZqzDtbXcdpyBIHvGsnGp3G8HUZvNRQnqKb/tiDDa /8gRzlsO0mFlN1HfBZJlLUWuicj+uV2qjtwfdZkktzD10UkpbbIXKzfP pKx5H77tzcsCa+3x1jzoF5/c0nTi3gLJLxfOVbpZEf1r9KPgxPErzXIl dxl1fP59V3bRLgznNh0TA2t1/+cP4imXyL8LZp3y7NW2nR91ARegGznX 9b5+lCN4WR2vxTU+s3YIbtHNN9bVScC+w58dVNRN4AylniN4ofGnsUpH C/t2uA3rNsSUzBbMbmFJCx9v2+nEB8ki5KSBrrSy8UIvOLLiD527XD0F 8piFl0H9Ln0=
256 3 5 AwEAAeaymGqZKkBwMXSj90IWRVcIbGvlM3JhPdzTmYWeQJPyVGkqgihg IiT+R3ftJ0wRiUSNJSVmRIQYP3UnUUb9AV4ti5xStmAvWbGI+q9Poasg feK8ZghMKPkPTOsfmrNVXIYzOGzv6z5VEpXJG5e7Ho3gVFqXSQZDfwBb tFs/0y6L
DNSKEY 5 2 3600 20190329220145 20190227210145 36097 leurent.eu. W+MlbgrDHCgxHmPB4dLMyyXyDwDxGNiH2FnMDt06dr+vSJBwuVdxwvKo fbxehQRXi/lM0P+/RinWni5dWFhhyhSqQKZj/E+gjxEQEHCuMosGiNx7 LR1KaofLLpeYRo1xEf6YWcc5BjIkA+FB22bdfBVBLhPy9PL6qQO+TGjX rufhkEyaPfsLkXSPraAiAu7IPA+QgE2TbqalsxBHh7rS4g16z3C5yCk2 FaV9BL6W9Dua3Xwnf/xEhrq+befqCPCFl97nhKbBlvXYiZEoqY5jAugS cKTQfNTxPSzmnewKmb6PKmiI2w178gldIA9J+TbyzvMqpCF+AfgAFACw /5PaVA==
DNSKEY 5 2 3600 20190329220145 20190227210145 65487 leurent.eu. w8AAJG/p0pHZE1TRiRN8dPz/b4eUZexQRuJJ8Zdx9QMLWlkc2fo/Dm/a CrLGbpTALBEG0oAAMg7A4qH+pp/LPSwf3QcgfrMF3bo7gb+lqKGCoX6+ JU2t5vJDcNkvl2NgxohVgwS/k4+Z8+xloYqKc9FtisCujHO2n22Z45ez Cxc=

Certbot : Manage LetsEncrypt Certificate

Install certbot > 0.22 to get wildcard support

root@tidus:[~]# apt install certbot python-certbot-apache python3-certbot-dns-rfc2136

root@link:[~/LETSENCRYPT]# dnssec-keygen -a HMAC-SHA512 -b 512 -n HOST acme-challenge

Create a new cert for leurent.eu + *.leurent.eu

  • Method using DNS to authenticate
root@link:[~]# certbot -d leurent.eu -d "*.leurent.eu" certonly --dns-rfc2136 --dns-rfc2136-credentials ~/.secrets/certbot/rfc2136.ini --dns-rfc2136-propagation-seconds 10

Create a new cert for leurent.ch using webroot folder

  • Method creating a file in the web folder
root@tidus:[~]# certbot --authenticator webroot --installer apache --webroot-path /home/web/www.leurent.ch -d leurent.ch -d www.leurent.ch

Force Renewal

root@tidus:[~]# certbot renew --force-renewal


Apache + GeoIP

  • Install the needed packages ( NB: You need the contrib repo enabled )
apt install libapache2-mod-geoip geoip-bin geoip-database-contrib
  • Here is an extract of /etc/apache2/conf-enabled/cacti.conf to enable GeoIP Restriction
Alias /cacti /usr/share/cacti/site

# Enable Geoip Module
GeoIPEnable On
GeoIPDBFile /usr/share/GeoIP/GeoIP.dat IndexCache
GeoIPDBFile /usr/share/GeoIP/GeoIPv6.dat IndexCache
# Allow only connection from Switzerland or France
SetEnvIf GEOIP_COUNTRY_CODE FR AllowCountry_cacti
SetEnvIf GEOIP_COUNTRY_CODE_V6 FR AllowCountry_cacti
SetEnvIf GEOIP_COUNTRY_CODE CH AllowCountry_cacti
SetEnvIf GEOIP_COUNTRY_CODE_V6 CH AllowCountry_cacti
<Directory /usr/share/cacti/site>
        Options +FollowSymLinks
        AllowOverride None
        <IfVersion >= 2.3>
                Require env AllowCountry_cacti
                #Require all granted
        <IfVersion < 2.3>
                Order Allow,Deny
                Allow from env=AllowCountry_cacti

        AddType application/x-httpd-php .php

        <IfModule mod_php5.c>
                php_flag magic_quotes_gpc Off
                php_flag short_open_tag On
                php_flag register_globals Off
                php_flag register_argc_argv On
                php_flag track_vars On
                # this setting is necessary for some locales
                php_value mbstring.func_overload 0
                php_value include_path .

        DirectoryIndex index.php

Iptables + GeoIP

  • Install the needed packages
apt install xtables-addons-dkms libtext-csv-xs-perl libnet-cidr-lite-perl
  • Get the /usr/lib/xtables-addons/xt_geoip_dl and /usr/lib/xtables-addons/xt_geoip_build of xtables-addons 3.2

  • Here is the cron file I use to download and format everything : /etc/cron.monthly/geoip

# apt install libnet-cidr-lite-perl libtext-csv-xs-perl

# Create Archives folder

# Download Last Version of GeoLite2-Country

# build copy GeoLite2 Country Databases
cd $XTGEOIP/GeoLite2-Country-CSV_*
/usr/lib/xtables-addons/xt_geoip_build -D $XTGEOIP $XTGEOIP/GeoLite2-Country-CSV_*/*.csv

# remove download GeoLite2 Country Database
rm $XTGEOIP/GeoLite2-Country-CSV_* -rf

SpamAssassin + GeoIP

apt install libgeo-ip-perl

Kibana + Elasticsearch + Logstash: Log Analyser

Kibana is a really powerful log analyser ( big data gathering and analyse )

wget -qO - https://artifacts.elastic.co/GPG-KEY-elasticsearch | sudo apt-key add -
echo "deb https://artifacts.elastic.co/packages/6.x/apt stable main" | sudo tee -a /etc/apt/sources.list.d/elastic-6.x.list
echo "deb [arch=amd64] https://packages.elastic.co/curator/5/debian9 stable main" | sudo tee -a /etc/apt/sources.list.d/curator.list
apt update
apt install kibana elasticsearch elasticsearch-curator python-elasticsearch logstash 

systemctl enable logstash.service
systemctl enable elasticsearch.service
systemctl enable kibana.service

systemctl start logstash.service
systemctl start elasticsearch.service
systemctl start kibana.service

LDAP user backend

  • Install slapd
apt install slapd
dpkg-reconfigure slapd
  • Backup old server
 slapcat -n 0 -l /root/LDAP/slapcat_config_`date +%Y%m%d`.ldif && slapcat -n 1 -l /root/LDAP/slapcat_data_`date +%Y%m%d`.ldif
  • Shutdown ldap server
systemctl stop slapd
  • Delete config and import config from backup
tar cvzf /root/LDAP/slapd.d_OLD.tgz /etc/ldap/slapd.d && rm -r /etc/ldap/slapd.d
mkdir /etc/ldap/slapd.d
slapadd -n 1 -F /etc/ldap/slapd.d -l /root/LDAP/slapcat_data_`date +%Y%m%d`.ldif
chown -R openldap:openldap /etc/ldap/slapd.d
  • Import Data
tar cvzf /root/LDAP/LDAP-old-data.tgz /var/lib/ldap && rm -r /var/lib/ldap
mkdir /var/lib/ldap
slapadd -n 1 -F /etc/ldap/slapd.d -l /root/LDAP/slapcat_data_`date +%Y%m%d`.ldif
chown -R openldap:openldap /var/lib/ldap
  • Restart LDAP server
systemctl start slapd
  • Install libpam-ldap and libnss-ldap and nscd
# You will be asked for the admin account + an unpriviledged account
apt install libnss-ldap libpam-ldap
  • Update /etc/nsswitch.conf to add ldap
--- /etc/nsswitch.conf.old      2019-07-20 10:02:48.743787771 +0200
+++ /etc/nsswitch.conf  2019-07-20 10:14:12.422547865 +0200
@@ -4,9 +4,9 @@
 # If you have the `glibc-doc-reference' and `info' packages installed, try:
 # `info libc "Name Service Switch"' for information about this file.
-passwd:         files systemd
-group:          files systemd
-shadow:         files
+passwd:         files systemd ldap
+group:          files systemd ldap
+shadow:         files ldap
 gshadow:        files
 hosts:          files dns
zsh: exit 1     diff -u /etc/nsswitch.conf.old /etc/nsswitch.conf

Install Phpldapadmin

  1. Verify if it is available in a backport
apt install phpldapadmin php-xml
  1. Disable anonymous-read


opkg install softflowd
softflowctl expire-all

 Mail Platform

apt install postfix spamassassin postfix-policyd-spf-python
apt install dovecot-imapd dovecot-managesieved dovecot-pop3d dovecot-sieve
apt install roundcube roundcube-mysql roundcube-plugins php-zip php-net-sieve
Update innodb_log_file_size=2024MB for the attachement upload

Email AutoDiscover

cf https://wiki.mozilla.org/Thunderbird:Autoconfiguration


figlet to create ASCII test

(SSH):marc@cloud:[~]$ figlet cloud
      _                 _ 
  ___| | ___  _   _  __| |
 / __| |/ _ \| | | |/ _` |
| (__| | (_) | |_| | (_| |
 \___|_|\___/ \__,_|\__,_|

Example of usage

root@cloud:[/etc/update-motd.d]# cat /etc/update-motd.d/10-logo
# Display the hostname with a fancy ASCII mode
figlet -w 120 -t `hostname -f``