No.Try not. Do… or do not. There is no try.

Find Who Is Logged in by Ssh Key Fingerprint


Old debian based OS

$ grep 'Accepted publickey' /var/log/auth.log
...
Oct 12 07:09:05 <hostname> sshd[54321]: Accepted publickey for <username> from <ip> port 12345 ssh2: ED25519 00:00:00:00:00:00:00:00:00:00:00:00:00:00
...

sudo -i -u username sh -c  'cat ~/.ssh/authorized_keys | sed "s/^/localhost /" > /tmp/authorized_keys'
ssh-keygen -l -f /tmp/authorized_keys | grep 00:00:00:00:00:00:00:00:00:00:00:00:00:00
256 00:00:00:00:00:00:00:00:00:00:00:00:00:00  user@example.com (ED25519)

Modern RHEL/Debian based OS

$ journalctl -u sshd | grep 'Accepted publickey'
Oct 12 01:02:04 <hostname> sshd[54321]: Accepted publickey for <username> from <ip> port 12345 ssh2: ECDSA SHA256:ABCDEFGabcdefgABCDEFGabcdefgABCDEFGabcdefg
Oct 12 01:07:16 <hostname> sshd[54322]: Accepted publickey for <username> from <ip> port 12346 ssh2: RSA SHA256:abcdefgABCDEFGabcdefgABCDEFGabcdefgABCDEFG
Oct 12 07:24:13 <hostname> sshd[54323]: Accepted publickey for <username> from <ip> port 12347 ssh2: RSA SHA256:DEFGabcdefgABCDEFGabcdefgABCDEFGabcdefgABC

sudo -i -u username sh -c 'ssh-keygen -l -f ~/.ssh/authorized_keys'
2048 SHA256:abcdefgABCDEFGabcdefgABCDEFGabcdefgABCDEFG user1@example.com (RSA)
521 SHA256:ABCDEFGabcdefgABCDEFGabcdefgABCDEFGabcdefg user2@example.com (ECDSA)
4096 SHA256:DEFGabcdefgABCDEFGabcdefgABCDEFGabcdefgABC user3@example.com (RSA)
…
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SSH Passwordless Login With Keychain


Install Keychain

dnf install keychain -y
# apt-get install keychain -y
# pkg install keychain -y

Generate a new ssh key if not exist

ssh-keygen -t ecdsa-sha2-nistp256 -C $USERNAME -f ~/.ssh/$USERNAME

Assign the pass phrase when prompted.

How to use Keychain

Update your $HOME/.bash_profile file or simular initialization file for zsh, fish, etc.

vi $HOME/.bash_profile

Append the following code:

alias sshkey_secured="keychain $USERNAME --nogui --quiet --timeout 60 ; source ~/.keychain/$HOSTNAME-sh"
source ~/.keychain/$HOSTNAME-sh

Run once in the same terminal to update environment:

…
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install selfhosted internal mailinator


Setup domain

  • Log in https://my.freenom.com/
  • buy yourdomain.here for $0/year
  • set glue records:
    KLEY.yourdomain.here - xxx.yyy.zzz.abc
YELK.yourdomain.here - xxx.yyy.zzz.abc
  • Use custom nameservers:
    KLEY.yourdomain.here
YELK.yourdomain.here

Setup DNS service

sudo -i
dnf install bind bind-utils
cat > /etc/named.conf << TOLIK
options {
        listen-on port 53 { any; };
        listen-on-v6 port 53 {  none; };

        directory       "/var/named";
        dump-file       "/var/named/data/cache_dump.db";
        statistics-file "/var/named/data/named_stats.txt";
        memstatistics-file "/var/named/data/named_mem_stats.txt";
        secroots-file   "/var/named/data/named.secroots";
        recursing-file  "/var/named/data/named.recursing";
        recursion no;
        dnssec-enable no;
        dnssec-validation no;
        managed-keys-directory "/var/named/dynamic";
        pid-file "/run/named/named.pid";
        session-keyfile "/run/named/session.key";
        include "/etc/crypto-policies/back-ends/bind.config";
};

logging {
        channel default_debug {
                file "data/named.run";
                severity dynamic;
        };
};

zone "." IN {
        type hint;
        file "named.ca";
};

include "/etc/named.rfc1912.zones";
include "/etc/named.root.key";

zone "yourdomain.here" {
        type master;
        file "yourdomain.here.hosts";
        allow-transfer {
                127.0.0.1;
                localnets;
                };
        };

TOLIK


cat > /var/named/yourdomain.here.hosts << TOLIK
\$ttl 38400
@  IN  SOA  yourdomain.here. root.yourdomain.here. (
            1461722457
            10800
            3600
            604800
            38400 )
yourdomain.here.  IN  A  xxx.yyy.zzz.abc
kley.yourdomain.here. IN      A       xxx.yyy.zzz.abc
yelk.yourdomain.here. IN      A       xxx.yyy.zzz.abc
yourdomain.here.  IN  MX  5 yourdomain.here.
@  IN  NS  kley.yourdomain.here.
@  IN  NS  yelk.yourdomain.here.

TOLIK


named-checkconf /etc/named.conf
named-checkzone  yourdomain.here  /var/named/yourdomain.here.hosts 
# zone yourdomain.here/IN: loaded serial 1461722457
# OK

Setup MAIL service

mkdir /srv/inbucket
chown daemon:daemon /srv/inbucket
dnf install -y https://github.com/inbucket/inbucket/releases/download/v3.0.0-beta3/inbucket_3.0.0-beta3_linux_amd64.rpm

mkdir /etc/systemd/system/inbucket.service.d/

cat > /etc/systemd/system/inbucket.service.d/override.conf << TOLIK
[Service]
Environment=INBUCKET_SMTP_ADDR=0.0.0.0:25
Environment=INBUCKET_SMTP_DOMAIN=yourdomain.here
Environment=INBUCKET_SMTP_MAXRECIPIENTS=2000
Environment=INBUCKET_SMTP_DEFAULTACCEPT=false
Environment=INBUCKET_SMTP_ACCEPTDOMAINS=yourdomain.here
Environment=INBUCKET_POP3_DOMAIN=yourdomain.here
Environment=INBUCKET_POP3_ADDR=127.0.0.1:1100
Environment=INBUCKET_WEB_ADDR=0.0.0.0:80
Environment=INBUCKET_WEB_MAILBOXPROMPT=@yourdomain.here
Environment=INBUCKET_WEB_MONITORHISTORY=1000
Environment=INBUCKET_STORAGE_TYPE=file
Environment=INBUCKET_STORAGE_PARAMS=path:/srv/inbucket
Environment=INBUCKET_STORAGE_RETENTIONPERIOD="8760h"
Environment=INBUCKET_STORAGE_RETENTIONSLEEP="3600s"
Environment=INBUCKET_STORAGE_MAILBOXMSGCAP="0"

NonBlocking=true
NoNewPrivileges=yes
CapabilityBoundingSet=CAP_NET_BIND_SERVICE
AmbientCapabilities=CAP_NET_BIND_SERVICE
LimitNOFILE=500000
LimitNPROC=500000

TOLIK

systemctl start inbucket
systemctl status inbucket
systemctl enable inbucket
…
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google-chrome: clean passwords


Run google-chrome with –password-store=basic (example)

dnf install sqliteman  
cp ~/.config/google-chrome/Default/Web\ Data{,.bak}  
sqliteman ~/.config/google-chrome/Default/Web\ Data
…
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