Posts on TECHNERDONLINE

Bastion Host On DigitalOcean

Sun, 23 May 2021 21:17:12 +0600

What is a Bastion Host?

A bastion host is a special-purpose computer on a network specifically designed and configured to withstand attacks. There are two common network configurations that include bastion hosts and their placement.

The first requires two firewalls, with bastion hosts sitting between the first “outside world” firewall, and an inside firewall, in a DMZ. Often, smaller networks do not have multiple firewalls, so if only one firewall exists in a network, bastion hosts are commonly placed outside the firewall.

Getting Started

You can use the referral badge below to get started with a $100 credit from Digital Ocean or use this link to DigitalOcean.

DigitalOcean VPC

On 7 April, 2020, the VPC service replaced the Private Networking service on DigitalOcean.

A Virtual Private Cloud (VPC) is a private network interface for collections of DigitalOcean resources. VPC networks provide a more secure connection between resources because the network is inaccessible from the public internet and other VPC networks. Traffic within a VPC network doesn’t count against bandwidth usage.

VPC are available at no additional cost and are enabled by default. They serve the same function as VLANs do. You have two options, you can either manual create a VPC network or if you don’t have a VPC network DigitalOcean will create it for you when you build a new VPS.

DigitalOcean Cloud Firewalls

Cloud Firewalls affect both public and VPC network traffic. Rules specific to either must specify the public or private IP range.

We will be creating two cloud firewall rules, one named public-network and the other named private-network. These will be used as Access Control Lists to help protect our VPC network.

Both the Public-Network and Private-Network cloud firewalls should be added to the bastion-host, while only the Private-Network cloud firewall should be added to all other members of your VPS.

PUBLIC-NETWORK

INBOUND RULES :

Type	Protocol	Port Range	Sources
ICMP	ICMP	None	All IPv4, All IPv6
SSH	TCP	22	All IPv4, All IPv6
HTTP	TCP	80	All IPv4, All IPv6
HTTPS	TCP	443	All IPv4, All IPv6
CUSTOM	UDP	51820	All IPv4, All IPv6

OUTBOUND RULES :

Type	Protocol	Port Range	Sources
ICMP	ICMP	None	All IPv4, All IPv6
All TCP	TCP	All Ports	All IPv4, All IPv6
All UDP	UDP	All Ports	All IPv4, All IPv6

PRIVATE-NETWORK

INBOUND RULES :

Type	Protocol	Port Range	Sources
ICMP	ICMP	None	10.0.0.0/8, 172.16.0.0/12, 192.168.0.0/16
All TCP	TCP	All Ports	10.0.0.0/8, 172.16.0.0/12, 192.168.0.0/16
All UDP	UDP	All Ports	10.0.0.0/8, 172.16.0.0/12, 192.168.0.0/16

OUTBOUND RULES :

Type	Protocol	Port Range	Sources
ICMP	ICMP	None	All IPv4
All TCP	TCP	All Ports	All IPv4
All UDP	UDP	All Ports	All IPv4

I also recommend creating new ssh keys to add to your bastion-host.

ssh-keygen -b 4096  -a 1000 -t rsa -f ~/.ssh/id_rsa

Let’s lock down your ssh service.

$ sudo mv /etc/ssh/sshd_config /etc/ssh/sshd_config.bak

# Harden SSH Settings
$ sudo cat <<-EOF > /etc/ssh/sshd_config
HostKey /etc/ssh/ssh_host_ed25519_key
HostKey /etc/ssh/ssh_host_rsa_key
HostKey /etc/ssh/ssh_host_ecdsa_key
AcceptEnv LANG LC_*
AllowGroups root sudo
Banner /etc/issue.net
ChallengeResponseAuthentication no
Ciphers chacha20-poly1305@openssh.com,aes256-gcm@openssh.com,aes256-ctr
ClientAliveCountMax 0
ClientAliveInterval 300
Compression no
HostbasedAuthentication no
IgnoreUserKnownHosts yes
KexAlgorithms curve25519-sha256@libssh.org,ecdh-sha2-nistp521,ecdh-sha2-nistp384,ecdh-sha2-nistp256,diffie-hellman-group-exchange-sha256
LoginGraceTime 20
LogLevel VERBOSE
Macs hmac-sha2-512-etm@openssh.com,hmac-sha2-256-etm@openssh.com,hmac-sha2-512,hmac-sha2-256
MaxAuthTries 3
MaxSessions 3
MaxStartups 10:30:60
PermitEmptyPasswords no
PermitRootLogin no
PubkeyAuthentication yes
PasswordAuthentication no
PermitUserEnvironment no
PrintLastLog yes
PrintMotd no
StrictModes yes
Subsystem sftp internal-sftp
UseDNS no
UsePAM yes
X11Forwarding no
AllowTcpForwarding yes
EOF

Create a new set of ssh host keys.

## Update ssh_host keys
rm /etc/ssh/ssh_host_*
ssh-keygen -t ecdsa -b 521 -f /etc/ssh/ssh_host_ecdsa_key -N ""
ssh-keygen -t rsa -b 4096 -f /etc/ssh/ssh_host_rsa_key -N ""
ssh-keygen -t ed25519 -f /etc/ssh/ssh_host_ed25519_key -N ""

awk '$5 >= 3071' /etc/ssh/moduli > /etc/ssh/moduli.safe
mv /etc/ssh/moduli.safe /etc/ssh/moduli

We need to edit the netplan for both the bastion-host and the webproxy so that the bastion-host handles all routing.

sudo nano /etc/netplan/50-cloud-init.yaml

You can read more details on editing your netplan on DigitalOcean.

network:
    version: 2
    ethernets:
        eth0:
            addresses:
            - xxx.xxx.xxx.xxx/20
            - 26xx:xxxx:x:xxx::xx:xxxx/64
            gateway4: xxx.xxx.xxx.1
            gateway6: 26xx:xxxx:x:xxx::1
            match:
                macaddress: ab:ab:ab:ab:ab:ab
            nameservers:
                addresses:
                - 1.1.1.1
                - 1.0.0.1
                - 2606:4700:4700::1111
                - 2606:4700:4700::1001
                search: [technerdonline.com]
        eth1:
            addresses:
            - 10.128.0.2/20
            match:
                macaddress: ba:ba:ba:ba:ba:ba
            nameservers:
                addresses:
                - 10.128.0.2
                search: [local]
            routes:
            -   to: 10.128.0.0/20
                via: 10.128.0.2

On the proxy server make the following netplan change.

network:
    version: 2
    ethernets:
        eth0:
            addresses:
            - xxx.xxx.xxx.xxx/20
            - 26xx:xxxx:x:xxx::xx:xxxx/64
            #gateway4: xxx.xxx.xxx.1
            #gateway6: 26xx:xxxx:x:xxx::1
            match:
                macaddress: ab:ab:ab:ab:ab:ab
            nameservers:
                addresses:
                - 1.1.1.1
                - 1.0.0.1
                - 2606:4700:4700::1111
                - 2606:4700:4700::1001
                search: [technerdonline.com]
        eth1:
            addresses:
            - 10.128.0.3/20
            match:
                macaddress: ba:ba:ba:ba:ba:ba
            nameservers:
                addresses:
                - 10.128.0.2
                search: [local]
            routes:
            -   to: 0.0.0.0/0
                via: 10.128.0.2

Apply the netplan changes.

sudo netplan apply

We will need to create a set of IPTABLES rules for both IPv4 and IPv6 but first we need to load some Kernel modules.

sudo nano /etc/modules-load.d/iptables.conf

overlay
br_netfilter
ip_vs
ip_vs_rr
ip_vs_wrr
ip_vs_sh
nf_conntrack
iptable_nat
iptable_filter
iptable_mangle
ip_nf_target_redirect
ip_set
ip_vs_nfct
ip_vs_proto_tcp
ip_vs_proto_udp
veth
bridge
bridge_netfilter
ip_nf_filter
ip_nf_target_masquerade
netfilter_xt_match_addrtype
netfilter_xt_match_conntrack
netfilter_xt_match_ipvs
nf_nat

Copy and paste the following content, replacing PUBLIC_IP with the public IP address of the bastion-host, WEBPROXY_PRIVATE_IP with the VPC IP address for the webproxy, and BASTION_PRIVATE_IP with the VPC IP address with the bastion host private IP.

nano ipv4.conf

*mangle
:PREROUTING ACCEPT [0:0]
:INPUT ACCEPT [0:0]
:FORWARD ACCEPT [0:0]
:OUTPUT ACCEPT [0:0]
:POSTROUTING ACCEPT [0:0]
COMMIT

*nat
:PREROUTING ACCEPT [0:0]
:INPUT ACCEPT [0:0]
:OUTPUT ACCEPT [0:0]
:POSTROUTING ACCEPT [0:0]
-A PREROUTING -i eth0 -d {PUBLIC_IP} -p tcp -m tcp --dport 80 -j DNAT --to-destination {WEBPROXY_PRIVATE_IP}:80
-A PREROUTING -i eth0 -d {PUBLIC_IP} -p tcp -m tcp --dport 443 -j DNAT --to-destination {WEBPROXY_PRIVATE_IP}:443
-A POSTROUTING -d {WEBPROXY_PRIVATE_IP} -o eth1 -p tcp -m tcp --dport 80 -j SNAT --to-source {BASTION_PRIVATE_IP}
-A POSTROUTING -d {WEBPROXY_PRIVATE_IP} -o eth1 -p tcp -m tcp --dport 443 -j SNAT --to-source {BASTION_PRIVATE_IP}
-A POSTROUTING -s {BASTION_PRIVATE_IP} -o eth0 -j SNAT --to-source {PUBLIC_IP}
-A POSTROUTING -s {PRIVATE_SUBNET} ! -d {PRIVATE_SUBNET} -j MASQUERADE
COMMIT

*filter
:INPUT DROP [0:0]
:FORWARD DROP [0:0]
:OUTPUT ACCEPT [0:0]
:FILTERS - [0:0]
-A INPUT -m conntrack --ctstate RELATED,ESTABLISHED -j ACCEPT
-A INPUT -i lo -j ACCEPT
-A INPUT -m conntrack --ctstate INVALID -j DROP
-A INPUT -p icmp -m icmp --icmp-type 8 -m limit --limit 5/sec -j ACCEPT
-A INPUT -i eth1 -m conntrack --ctstate NEW -s {PRIVATE_SUBNET} -j ACCEPT
-A INPUT -j FILTERS
-A INPUT -j DROP
-A FORWARD -o eth1 -m conntrack --ctstate RELATED,ESTABLISHED -j ACCEPT
-A FORWARD -i eth1 -o eth1 -m conntrack --ctstate NEW -s {PRIVATE_SUBNET} -j ACCEPT
-A FORWARD -o eth0 -m conntrack --ctstate RELATED,ESTABLISHED -j ACCEPT
-A FORWARD -i eth1 -o eth0 -m conntrack --ctstate NEW -s {PRIVATE_SUBNET} -j ACCEPT
-A FORWARD -i eth0 -o eth1 -j FILTERS
-A OUTPUT -o lo -j ACCEPT
-A OUTPUT -o eth0 -j ACCEPT
-A OUTPUT -o eth1 -j ACCEPT
-A FILTERS -m conntrack --ctstate RELATED,ESTABLISHED -j ACCEPT
-A FILTERS -p tcp -m conntrack --ctstate NEW -m tcp --syn --dport 22 -j ACCEPT
-A FILTERS -p tcp -m conntrack --ctstate NEW -m tcp --syn --dport 80 -j ACCEPT
-A FILTERS -p tcp -m conntrack --ctstate NEW -m tcp --syn --dport 443 -j ACCEPT
-A FILTERS -p udp -m conntrack --ctstate NEW -m udp --dport 51820 -j ACCEPT
-A FILTERS -p udp -m conntrack --ctstate NEW -m udp --dport 51821 -j ACCEPT
-A FILTERS -m conntrack --ctstate INVALID -j DROP
-A FILTERS -j REJECT
COMMIT

Now create IPTABLES Rules for IPv6.

nano ipv6.conf

*nat
:PREROUTING ACCEPT [0:0]
:INPUT ACCEPT [0:0]
:OUTPUT ACCEPT [0:0]
:POSTROUTING ACCEPT [0:0]
COMMIT

*filter
:INPUT DROP [0:0]
:FORWARD DROP [0:0]
:OUTPUT ACCEPT [0:0]
:FILTERS - [0:0]
-A INPUT -m conntrack --ctstate RELATED,ESTABLISHED -j ACCEPT
-A INPUT -i lo -j ACCEPT
-A INPUT -m conntrack --ctstate INVALID -j DROP
-A INPUT -i eth0 -p ipv6-icmp -m icmp6 --icmpv6-type 128 -m limit --limit 5/sec -j ACCEPT
-A INPUT -i eth0 -p ipv6-icmp -m icmp6 --icmpv6-type 133 -m limit --limit 5/sec -j ACCEPT
-A INPUT -i eth0 -p ipv6-icmp -m icmp6 --icmpv6-type 134 -m limit --limit 5/sec -j ACCEPT
-A INPUT -i eth0 -p ipv6-icmp -m icmp6 --icmpv6-type 135 -m limit --limit 5/sec -j ACCEPT
-A INPUT -j FILTERS
-A INPUT -j DROP
-A FILTERS -m conntrack --ctstate RELATED,ESTABLISHED -j ACCEPT
-A FILTERS -p tcp -m conntrack --ctstate NEW -m tcp --dport 80 --tcp-flags FIN,SYN,RST,ACK SYN -j ACCEPT
-A FILTERS -p tcp -m conntrack --ctstate NEW -m tcp --dport 443 --tcp-flags FIN,SYN,RST,ACK SYN -j ACCEPT
-A FILTERS -m conntrack --ctstate INVALID -j DROP
-A FILTERS -j REJECT
-A OUTPUT -o lo -j ACCEPT
-A OUTPUT -o eth0 -j ACCEPT
-A OUTPUT -o eth1 -j ACCEPT
-A FORWARD -o eth1 -m conntrack --ctstate RELATED,ESTABLISHED -j ACCEPT
-A FORWARD -i eth1 -o eth1 -j FILTERS
-A FORWARD -o eth0 -m conntrack --ctstate RELATED,ESTABLISHED -j ACCEPT
-A FORWARD -i eth1 -o eth0 -m conntrack --ctstate NEW -j ACCEPT
-A FORWARD -i eth0 -o eth1 -j FILTERS
-A FORWARD -j REJECT
COMMIT

Apply the iptables rules and install iptables-persistent.

sudo iptables-restore -n ipv4.conf
sudo ip6tables-restore -n ipv6.conf

sudo iptables-save
sudo ip6tables-save

sudo apt install iptables-persistent

Simply install your favorite web server on the proxy droplet (i.e. nginx, caddy, haproxy etc). I would also suggest installing wireguard on the bastion host, it is also pretty easy to get a secure wireguard mesh network setup if you have multiple VPC.

Hardening Your Cloud Server

Sun, 23 May 2021 21:17:12 +0600

Taking the extra steps to protect your Ubuntu or Debian cloud droplet takes only a little effort and time but will have a huge long term impact on your cyber security. You can use the referral badge below to get started with a $100 credit from Digital Ocean or use this link to DigitalOcean.

1. ASSESS & IDENTIFY THE RISK

Undertaking a review to identify potential risks is a important first step. Some useful techniques for identifying risks are:

NMAP is a great tool to help identify potential risks. DigitalOcean has a pretty good guide here.
Tenable offers a great solution that also provides a very friendly report. Although normally a Nessus Professional license isn’t cheap, Tenable does offer a free version as well. You can download the free version here.
Sn1per is a open source solution that puts together a number of great open projects to deliver a very effective and easy to use package. You can check out the project on Github here.
Lynis is a open source tool that audits and grades your linux operating system’s security. You can check out the project on Github here.

2. REDUCE THE RISK

Once you have an idea of what potential cyber security risks you face you should start to take the steps to reduce those risks.

Set the default user profile to “umask 027” it is a good compromise between security and simplicity. A umask setting of 077 causes files and directories created by users to not be readable by any other user on the system. A umask of 027 makes files and directories readable by users in the same Unix group (i.e. “sudo” or “root”), while a umask of 022 makes files readable by every user on the system.

# Setting global umask
sudo echo "umask 027" >> /etc/profile

Restrict at and cron to authorized users only.

# First Remove both at.deny & cron.deny
sudo rm /etc/cron.deny 2> /dev/null
sudo rm /etc/at.deny 2> /dev/null
# Second create both at.allow & cron.allow
sudo echo 'root' > /etc/cron.allow
sudo echo 'root' > /etc/at.allow
# Third set the ownership to root
sudo chown root:root /etc/cron*
sudo chown root:root /etc/at*

Use the hosts.allow and hosts.deny files to help restrict access to services. For example the only IP address that should have access to NRPE on port 5666 is your Nagios server.

# Setup Some Access Control Rules
sudo echo 'sshd : ALL : ALLOW' > /etc/hosts.allow
# Or if this Node should only be accessible via a bastion-host
sudo echo 'sshd: 192.168.0.2' > /etc/hosts.allow
sudo echo 'ALL: LOCAL, 127.0.0.1' >> /etc/hosts.allow
sudo echo 'NRPE: 192.168.0.2' >> /etc/hosts.allow
sudo echo 'ALL: PARANOID' > /etc/hosts.deny
sudo chmod 644 /etc/hosts.allow
sudo chmod 644 /etc/hosts.deny

Limit visibility of running processes to those services that started the process or users in the same group.

# Edit fstab & Hide PID2
sudo echo 'proc /proc proc defaults,hidepid=2 0 0' >> /etc/fstab

Disable Root Recovery console, but make sure you have set a root password first.

# GRUB enable swap & disable root recovery
sudo echo 'GRUB_CMDLINE_LINUX="cgroup_enable=memory swapaccount=1"' >> /etc/default/grub
sudo echo 'GRUB_DISABLE_RECOVERY="true"' >> /etc/default/grub
sudo update-grub

It may seem unimportant, but having the time stamps match your timezone will make things easier later on when you are reviewing your logs and reports.

# Setup NTP
sudo timedatectl set-ntp true
sudo timedatectl set-timezone America/Los_Angeles
sudo echo 'servers=0.pool.ntp.org 1.pool.ntp.org 2.pool.ntp.org 3.pool.ntp.org' >> /etc/systemd/timesyncd.conf

sudo apt update
sudo apt install apparmor apparmor-profiles apparmor-utils apparmor-easyprof -y
# Enforce apparmor profiles
sudo echo 'session optional pam_apparmor.so order=user,group,default' > /etc/pam.d/apparmor

sudo systemctl start apparmor.service
sudo systemctl enable apparmor.service

sudo apt update
sudo apt install libpam-tmpdir libpam-apparmor libpam-cracklib -y

Disable USB access on your cloud node.

# Install USBGuard
sudo apt update
sudo apt install usbguard -y
# Setting up USBGuard
sudo usbguard generate-policy > /tmp/rules.conf
sudo install -m 0600 -o root -g root /tmp/rules.conf /etc/usbguard/rules.conf

Securing your remote access services isn’t just about disabling root access and enabling authorized keys in your SSH configuration.

sudo mv /etc/ssh/sshd_config /etc/ssh/sshd_config.bak

# Harden SSH Settings
sudo cat <<-EOF > /etc/ssh/sshd_config
HostKey /etc/ssh/ssh_host_ed25519_key
HostKey /etc/ssh/ssh_host_rsa_key
HostKey /etc/ssh/ssh_host_ecdsa_key
AcceptEnv LANG LC_*
AllowGroups root sudo
Banner /etc/issue.net
ChallengeResponseAuthentication no
Ciphers chacha20-poly1305@openssh.com,aes256-gcm@openssh.com,aes256-ctr
ClientAliveCountMax 0
ClientAliveInterval 300
Compression no
HostbasedAuthentication no
IgnoreUserKnownHosts yes
KexAlgorithms curve25519-sha256@libssh.org,ecdh-sha2-nistp521,ecdh-sha2-nistp384,ecdh-sha2-nistp256,diffie-hellman-group-exchange-sha256
LoginGraceTime 20
LogLevel VERBOSE
Macs hmac-sha2-512-etm@openssh.com,hmac-sha2-256-etm@openssh.com,hmac-sha2-512,hmac-sha2-256
MaxAuthTries 3
MaxSessions 3
MaxStartups 10:30:60
PermitEmptyPasswords no
PermitRootLogin no
PubkeyAuthentication yes
PasswordAuthentication no
PermitUserEnvironment no
PrintLastLog yes
PrintMotd no
StrictModes yes
Subsystem sftp internal-sftp
UseDNS no
UsePAM yes
X11Forwarding no
AllowTcpForwarding no
EOF

sudo systemctl daemon-reload
sudo systemctl restart ssh.service

Now update your host keys and test ssh by starting a 2nd session.

## Switch to root
sudo su -
## Update ssh_host keys
rm /etc/ssh/ssh_host_*
ssh-keygen -t ecdsa -b 521 -f /etc/ssh/ssh_host_ecdsa_key -N ""
ssh-keygen -t rsa -b 4096 -f /etc/ssh/ssh_host_rsa_key -N ""
ssh-keygen -t ed25519 -f /etc/ssh/ssh_host_ed25519_key -N ""

awk '$5 >= 3071' /etc/ssh/moduli > /etc/ssh/moduli.safe
mv /etc/ssh/moduli.safe /etc/ssh/moduli

3. MANAGE YOUR RISK

sudo apt update
sudo apt install dbconfig-common dbconfig-sqlite3 sqlite3 fail2ban -y
sudo cp /etc/fail2ban/jail.conf /etc/fail2ban/jail.d/jail.local
sudo systemctl restart fail2ban

sudo apt update
sudo apt install rkhunter -y
sudo dpkg-reconfigure rkhunter

sudo cat <<-EOF > /etc/apt/apt.conf.d/20auto-upgrades
APT::Periodic::Update-Package-Lists "1";
APT::Periodic::Download-Upgradeable-Packages "1";
APT::Periodic::AutocleanInterval "7";
APT::Periodic::Unattended-Upgrade "1";
EOF

4. MONITOR YOUR RISK

Auditd can be a pretty powerful tool once you have the audit rules setup as it will give you valuable insights about your server performance and activities by ensuring that they are written to your logs.

sudo apt update
sudo apt install auditd audispd-plugins -y
# Setup Auditd Rules and Logging
sudo cat <<-EOF > /etc/audit/rules.d/docker.rules
# Remove any existing rules
-D
# Buffer Size
-b 8192
# Ignore errors
-i
# Failure Mode
-f 1
# Audit the audit logs
-w /var/log/audit/ -k auditlog
# Auditd configuration
-w /etc/audit/ -p wa -k auditconfig
-w /etc/libaudit.conf -p wa -k auditconfig
-w /etc/audisp/ -p wa -k audispconfig
# Monitor for use of audit management tools
-w /sbin/auditctl -p x -k audittools
-w /sbin/auditd -p x -k audittools
# Monitor AppArmor configuration changes
-w /etc/apparmor/ -p wa -k apparmor
-w /etc/apparmor.d/ -p wa -k apparmor
# Monitor usage of AppArmor tools
-w /sbin/apparmor_parser -p x -k apparmor_tools
-w /usr/sbin/aa-complain -p x -k apparmor_tools
-w /usr/sbin/aa-disable -p x -k apparmor_tools
-w /usr/sbin/aa-enforce -p x -k apparmor_tools
# Monitor Systemd configuration changes
-w /etc/systemd/ -p wa -k systemd
-w /lib/systemd/ -p wa -k systemd
# Monitor usage of systemd tools
-w /bin/systemctl -p x -k systemd_tools
-w /bin/journalctl -p x -k systemd_tools
# Special files
-a always,exit -F arch=x86_64 -S mknod -S mknodat -k specialfiles
-a always,exit -F arch=b32 -S mknod -S mknodat -k specialfiles
# Mount operations
-a always,exit -F arch=x86_64 -S mount -F auid>=1000 -F auid!=4294967295 -F key=export
-a always,exit -F arch=b32 -S mount -F auid>=1000 -F auid!=4294967295 -F key=export
# Changes to the time
-a always,exit -F arch=x86_64 -S settimeofday -k audit_time_rules
-a always,exit -F arch=x86_64 -S adjtimex -k audit_time_rules
-a always,exit -F arch=x86_64 -S clock_settime -k audit_time_rules
-a always,exit -F arch=b32 -S settimeofday -k audit_time_rules
-a always,exit -F arch=b32 -S adjtimex -k audit_time_rules
-a always,exit -F arch=b32 -S clock_settime -k audit_time_rules
# Cron configuration & scheduled jobs
-w /etc/cron.allow -p wa -k cron
-w /etc/cron.deny -p wa -k cron
-w /etc/cron.d/ -p wa -k cron
-w /etc/cron.daily/ -p wa -k cron
-w /etc/cron.hourly/ -p wa -k cron
-w /etc/cron.monthly/ -p wa -k cron
-w /etc/cron.weekly/ -p wa -k cron
-w /etc/crontab -p wa -k cron
-w /var/spool/cron/crontabs/ -k cron
# User, group, password databases
-w /etc/group -p wa -k audit_rules_usergroup_modification
-w /etc/passwd -p wa -k audit_rules_usergroup_modification
-w /etc/gshadow -p wa -k audit_rules_usergroup_modification
-w /etc/shadow -p wa -k audit_rules_usergroup_modification
-w /etc/security/opasswd -p wa -k audit_rules_usergroup_modification
# MAC-policy
-w /etc/selinux/ -p wa -k MAC-policy
# Monitor usage of passwd
-w /usr/bin/passwd -p x -k passwd_modification
# Monitor for use of tools to change group identifiers
-w /usr/sbin/groupadd -p x -k group_modification
-w /usr/sbin/groupmod -p x -k group_modification
-w /usr/sbin/addgroup -p x -k group_modification
-w /usr/sbin/useradd -p x -k user_modification
-w /usr/sbin/usermod -p x -k user_modification
-w /usr/sbin/adduser -p x -k user_modification
# Monitor module tools
-w /sbin/insmod -p x -k modules
-w /sbin/rmmod -p x -k modules
-w /sbin/modprobe -p x -k modules
-w /usr/sbin/insmod -p x -k modules
-w /usr/sbin/rmmod -p x -k modules
-w /usr/sbin/modprobe -p x -k modules
# Login configuration and information
-w /etc/login.defs -p wa -k login
-w /etc/securetty -p wa -k login
-w /var/log/faillog -p wa -k login
-w /var/run/faillock/ -p wa -k logins
-w /var/log/lastlog -p wa -k login
-w /var/log/tallylog -p wa -k login
# Network configuration
-w /etc/hosts -p wa -k audit_rules_networkconfig_modification
-w /etc/network/ -p wa -k audit_rules_networkconfig_modification
-w /etc/sysconfig/network -p wa -k audit_rules_networkconfig_modification
# System startup scripts
-w /etc/inittab -p wa -k init
-w /etc/init.d/ -p wa -k init
-w /etc/init/ -p wa -k init
# Library search paths
-w /etc/ld.so.conf -p wa -k libpath
# Local time zone
-w /etc/localtime -p wa -k localtime
# Time zone configuration
-w /etc/timezone -p wa -k audit_time_ruleszone
# Kernel parameters
-w /etc/sysctl.conf -p wa -k sysctl
# Modprobe configuration
-w /etc/modprobe.conf -p wa -k modprobe
-w /etc/modprobe.d/ -p wa -k modprobe
-w /etc/modules -p wa -k modprobe
# Module manipulations
-a always,exit -F arch=x86_64 -S init_module -S delete_module -F key=modules
-a always,exit -F arch=x86_64 -S init_module -F key=modules
-a always,exit -F arch=b32 -S init_module -S delete_module -F key=modules
-a always,exit -F arch=b32 -S init_module -F key=modules
# PAM configuration
-w /etc/pam.d/ -p wa -k pam
-w /etc/security/limits.conf -p wa -k pam
-w /etc/security/pam_env.conf -p wa -k pam
-w /etc/security/namespace.conf -p wa -k pam
-w /etc/security/namespace.init -p wa -k pam
# Postfix configuration
-w /etc/aliases -p wa -k mail
-w /etc/postfix/ -p wa -k mail
# SSH configuration
-w /etc/ssh/sshd_config -k sshd
# Changes to hostname
-a always,exit -F arch=x86_64 -S sethostname -S setdomainname -k audit_rules_networkconfig_modification
-a always,exit -F arch=b32 -S sethostname -S setdomainname -k audit_rules_networkconfig_modification
# Changes to issue
-w /etc/issue -p wa -k audit_rules_networkconfig_modification
-w /etc/issue.net -p wa -k audit_rules_networkconfig_modification
# Capture all unauthorized file accesses
-a always,exit -F arch=x86_64 -S creat -F exit=-EACCES -F auid>=1000 -F auid!=4294967295 -F key=access
-a always,exit -F arch=x86_64 -S creat -F exit=-EPERM -F auid>=1000 -F auid!=4294967295 -F key=access
-a always,exit -F arch=x86_64 -S openat -F exit=-EACCES -F auid>=1000 -F auid!=4294967295 -F key=access
-a always,exit -F arch=x86_64 -S openat -F exit=-EPERM -F auid>=1000 -F auid!=4294967295 -F key=access
-a always,exit -F arch=x86_64 -S open_by_handle_at -F exit=-EACCES -F auid>=1000 -F auid!=4294967295 -F key=access
-a always,exit -F arch=x86_64 -S open_by_handle_at -F exit=-EPERM -F auid>=1000 -F auid!=4294967295 -F key=access
-a always,exit -F arch=x86_64 -S truncate -F exit=-EACCES -F auid>=1000 -F auid!=4294967295 -F key=access
-a always,exit -F arch=x86_64 -S truncate -F exit=-EPERM -F auid>=1000 -F auid!=4294967295 -F key=access
-a always,exit -F arch=x86_64 -S ftruncate -F exit=-EPERM -F auid>=1000 -F auid!=4294967295 -F key=access
-a always,exit -F arch=x86_64 -S ftruncate -F exit=-EACCES -F auid>=1000 -F auid!=4294967295 -F key=access
-a always,exit -F arch=x86_64 -S open -F exit=-EACCES -F auid>=1000 -F auid!=4294967295 -F key=access
-a always,exit -F arch=x86_64 -S open -F exit=-EPERM -F auid>=1000 -F auid!=4294967295 -F key=access
-a always,exit -F arch=b32 -S open -F exit=-EACCES -F auid>=1000 -F auid!=4294967295 -F key=access
-a always,exit -F arch=b32 -S open -F exit=-EPERM -F auid>=1000 -F auid!=4294967295 -F key=access
-a always,exit -F arch=b32 -S creat -F exit=-EACCES -F auid>=1000 -F auid!=4294967295 -F key=access
-a always,exit -F arch=b32 -S creat -F exit=-EPERM -F auid>=1000 -F auid!=4294967295 -F key=access
-a always,exit -F arch=b32 -S openat -F exit=-EACCES -F auid>=1000 -F auid!=4294967295 -F key=access
-a always,exit -F arch=b32 -S openat -F exit=-EPERM -F auid>=1000 -F auid!=4294967295 -F key=access
-a always,exit -F arch=b32 -S open_by_handle_at -F exit=-EACCES -F auid>=1000 -F auid!=4294967295 -F key=access
-a always,exit -F arch=b32 -S open_by_handle_at -F exit=-EPERM -F auid>=1000 -F auid!=4294967295 -F key=access
-a always,exit -F arch=b32 -S truncate -F exit=-EACCES -F auid>=1000 -F auid!=4294967295 -F key=access
-a always,exit -F arch=b32 -S truncate -F exit=-EPERM -F auid>=1000 -F auid!=4294967295 -F key=access
-a always,exit -F arch=b32 -S ftruncate -F exit=-EACCES -F auid>=1000 -F auid!=4294967295 -F key=access
-a always,exit -F arch=b32 -S ftruncate -F exit=-EPERM -F auid>=1000 -F auid!=4294967295 -F key=access
# Monitor for use of process ID change (switching accounts) applications
-w /bin/su -p x -k actions
-w /usr/bin/sudo -p x -k actions
-w /etc/sudoers -p wa -k actions
-w /etc/sudoers.d -p wa -k actions
# Make the configuration immutable
-e 2
EOF

sudo systemctl start auditd
sudo systemctl enable auditd

You can then install logcheck or logwatch to get more detailed reports emailed to you. In addition you can use projects like mkcert or cfssl to enable TLS for internal communications between software like nrpe and nagios for example.

Follow this link for setting up a bastion screening host here or for my git project go here.

Improve Your Conferencing

Sat, 30 Jan 2021 14:51:12 +0600

Video Conferencing services have become extremely popular and are critical in facilitating professional face-to-face meetings between businesses. Using Quality of Service will improve your video conferencing experience. So when the video conferencing service isn’t performing well, latency, jitter, or dropped connections it can quickly become critical to your business to fix the problem as quickly as possible. Especially if the problem is happening across multiple video conferencing services.

I am going to suggest the first thing to check is that you have Quality of Service or QoS setup on your network devices. Video Conferencing services and Voice over IP for that matter all use UDP packets. UDP is a simple, stateless, and fast transport layer used by services and protocols that require speed such as real-time streaming protocols, Voice over IP, and streaming media services as well as online gaming services. While it is pretty straight forward, with little overhead their is no guaranteed or verification of the packets being received or the order of the packets.

A noisy network with either a lot of clients or traffic can cause enough latency or congestion to make for a poor video conferencing experience and in most cases it isn’t going to be an issue of inadequate bandwidth. Quality of Service or QoS manages the flow of traffic by prioritizing packets, preventing potential traffic jams, so network devices don’t have to drop packets entirely. It basically lets certain packets that match the rules that you have created to have priority over traffic that doesn’t match those same rules.

Essentially you can think of it like the car pool lane or toll road, any packets that are marked by the QoS policy as having priority are moved to the fast lane and are allowed to move ahead of packets with a lower priority. In order to get QoS setup you will need two pieces of information.

First your average upload/download bandwidth which you can get from any number of speed test sites. Second the UDP ports of the video conferencing service, for example Zoom’s UDP ports would be 3478-3479, and 8801-8810. QoS would need to be enabled and configured on the edge firewall as well as any network switches and routers the traffic would pass on the business’s network. For remote workers, most retail firewall support QoS and its a simple matter to enable and setup the ports, an example would be setting up Web Ex with a value of “7” while setting Netflix with a value of “6” and configuring HTTP, and HTTPS with a value of “4”. In this case you would be able to use Web Ex without performance issues while the kids are watching Netflix or surfing the web.

5 Steps To Stop Ransomware

Sat, 12 Sep 2020 12:52:36 +0600

“In an era of data breaches and identity theft, top-notch cyber security is essential for every enterprise, especially those doing business with the federal government. But with hackers constantly shifting tactics and new technologies continually emerging, doing so is a never-ending challenge.”

Here are 5 ways to protect your business from ransomware.

1. Setup a centralized patch management framework to keep your desktops and servers patched and updated against critical vulnerabilities :

Most modern operating systems now come with some type of patch management framework, Microsoft Windows users know this as Windows Updates. Ransomware exploits a critical vulnerability in Windows file sharing service to spread from one host to any host that is missing the critical patch that closes this vulnerability allowing the ransomware to spread with zero user interaction required. Windows Update Service or WUS is a service that allows for a centrally managed patch management framework for your business. Giving you the ability to not only schedule and automate patches but also to receive reports on what patches are installed, missing, and available and this service doesn’t require a paid subscription, or additional license other than a valid Windows server.

2. Use a vulnerability assessment solution to discover vulnerabilities and report vulnerabilities in your business :

Just like the service light on your car’s dashboard warns you of potential problems with your vehicle, you can use a vulnerability assessment server to run weekly or monthly scans of your business after hours and receive a human readable report of what vulnerabilities it has found and the possible solutions to correct the vulnerability. One of the best vulnerability assessment solutions is Nessus, while Nessus Professional costs a few thousand per year, you can use Nessus Essentials a free version that will scan up to 16 IP addresses, there are also a number of open source solutions such as open-vas, nmap etc. The key take away is that you need to know what and where your vulnerabilities are. Automating the scheduling and reporting every 30 days is a simple method of keeping yourself up to date on the ever changing cyber security threats. You want to be proactive.

3. Using network segmentation :

To give a better idea on how network segmentation works, picture the network as a office high rise with the different floors serving the same functions as different network segments. So a fire, flood, or other issue is contained to that floor. Network segmentation functions much the same way. This network segmentation would be used to divide different rolls or functions much the same as a company divides departments to different floors or offices. To further build on this, create different security zones on the firewall instead of the traditional untrusted/trusted model, create a security zone per functional role or group. An example could be remote-access, servers, users, WiFi, internet, and so forth. Finally setting ACL rules on the access layer switches and setting firewall rules to limit traffic between security zones.

4. Securing your DNS, the phone book of the internet :

The importance of securing both a businesses public and private DNS cannot be overstated. Many businesses using third party cloud mail services will add only the minimum required records to get the service working, the MX records. This leaves the business open to email spoofing and phishing attacks. Adding DKIM, SPF and DMARC records, helps identify the mail, tells who is allowed to talk to the mail server, and lets other mail servers know what you do with mail claiming to be from the mail server. Enabling DNSSEC allowing your DNS to be a trusted source by being able to validate DNS lookup. CAA records allows DNS to indicate to certificate authorities whether they are authorized to issue digital certificates for a particular domain name. Additionally setting up pi-hole or signing up for either Cisco Umbrella or Cloudflare Teams will reduce the chances of a ransomware attack by blocking domains being used by bad actors or domains that fail validation via DNSSEC. Businesses could always change the public dns being forwarded from 8.8.8.8 to 1.1.1.2.

5. Maintain working backups of all your key systems :

Every business should write down what at a minimum it needs to continue functioning, The list can get pretty large, 2 30 days sets of backups should be kept, one offsite and one on site, with the 30th backup set kept for 12 months. The most important part of this and one that I often see over looked is testing a full restore annually to ensure the documented steps are still valid.

How To Setup Meghna Hugo

Wed, 12 Sep 2018 14:51:12 +0600

Install this template by following those simple steps :

STEP-1 : Hugo installation

Check this link below for install hugo on your computer. hugo install documentation

STEP-2 : Create your project

Hugo provides a new command to create a new website.

hugo new site <new_project>

STEP-3 : Install the theme

Run this command

hugo new site meghna-hugo

and then go to the themes folder inside of meghna-hugo folder. You can also use this command cd meghna-hugo/themes for going to this folder. Then run the command

git clone git@github.com:themefisher/meghna-hugo.git

Alternatively, you can download the theme as .zip file and extract it in the themes directory

After that you need to go to the meghna-hugo/exampleSite folder and copy or cut all the elements, and now go back to the root folder and paste it here.

open the command prompt again and run cd ../ command for go back to the root folder.

STEP-4 : Host locally

Launching the website locally by using the following command:

hugo server

Go to http://localhost:1313

Or you can check this video documentation for installing this template:

STEP-5 : Basic configuration

When building the website, you can set a theme by using --theme option. However, we suggest you modify the configuration file (config.toml) and set the theme as the default.

# Change the default theme to be use when building the site with Hugo
theme = "meghna-hugo"

STEP-6 : Create your first content pages

hugo new blog/post-name.md

STEP-7 : Build the website

When your site is ready to deploy, run the following command:

hugo

# You can also create a minified version by using this command:
hugo --minify

A public folder will be generated, containing all static content and assets for your website. It can now be deployed on any web server.

You can use the referral badge below to get started with a $100 credit from Digital Ocean or use this link to DigitalOcean.