macOS: changing hostname

Primary hostname:

sudo scutil --set HostName KittyBook

Bonjour hostname (network related):

sudo scutil --set LocalHostName KittyBook.compukitty.net

Computer name (you can also do this via GUI, in System Preferences):

sudo scutil --set ComputerName <new name>

Create CSR for a SAN certificate

SAN stands for Subject Alternative Names and it allows you to use a single certificate for multiple CN.

It’s different from a wildcard certificate because with a SAN certificate you can have multiple complete CN (e.g. byruit.io, elena.com).

First, you have to create a .conf file with this content:

[ req ]
default_bits       = 4096
distinguished_name = req_distinguished_name
req_extensions     = req_ext
prompt             = no
[ req_distinguished_name ]
countryName                = Country Name (2 letter code)
stateOrProvinceName        = State or Province Name (full name)
localityName               = Locality Name (eg, city)
organizationName           = Organization Name (eg, company)
commonName                 = byruit.io
[ req_ext ]
subjectAltName = @alt_names
[alt_names]
DNS.1   = mail.compukitty.net
DNS.2   = monitor.compukitty.net
DNS.3   = compukitty.net
IP.1    = 10.130.8.7

The CN is the main domain you want to verify; ensure that this domain is also under the [alt_names]. You can add up to 250 domains.

Generate the CSR and KEY:

openssl req -new -out byruit.csr -newkey rsa:4096 -nodes -sha256 -keyout byruit.key -config san.conf

To verify the CSR:

openssl req -text -noout -verify -in byruit.csr

for loop to retrieve IPs using nslookup

I had to decommission a bunch of servers for which I didn’t have an IP list, needed for the paperwork.

Luckily, we still had the DNS records for those machines and, using a for loop and the almighty awk, I managed to retrieve all the information I needed:

for h in `cat hostname.list`; do nslookup $h | grep ^Name -A1 | awk '{print $2}'; echo; done > ip.list

This one-liner will output the IP and the corresponding hostname in a file.

route essential reference

Adding a route:

route add -net [net or host] gw [gw IP] netmask [mask] dev [interface]

Removing a route:

route del -net [net or host] gw [gw IP] netmask [mask] dev [interface]

Adding/removing a default route:

route add/del default gw [IP]

Listing routes using IPs:

route -n

Rejecting a specific host:

route add -host [IP] reject

fail2ban essential reference

Get the active jails:

# fail2ban-client status
Status
|- Number of jail: 1
`- Jail list: sshd

Show the banned IP in a jail:

# fail2ban-client status sshd
Status for the jail: sshd
|- Filter
| |- Currently failed: 3
| |- Total failed:     1907
| `- File list:        /var/log/secure 
`- Actions
  |- Currently banned: 0
  |- Total banned:     381
  `- Banned IP list:

You can also list the banned IPs using iptables -L.

Unban an IP:

fail2ban-client set [JAIL] unbanip [IP]

Ban an IP:

fail2ban-client set [JAIL] banip [IP]

Log file:

/var/log/fail2ban.log

Updating Solaris 11

Check if there are any updates available:

pkg list -u

-u will show only the packages for which updates are available.

Check the latest package version in the repository:

pkg info -r system/zones

(Optional) Perform a dry run:

pkg update -nv

Update:

pkg update