Linux CLI Deep Dive for PAM Engineers¶

Expert-level PAM (Privileged Access Management) administration explicitly requires GNU/Linux command-line skills, because the expert tasks — troubleshooting, the REST Application Programming Interface (API), proxy tuning, and high availability — happen at the shell of the PAM appliance, not just in the web GUI. Whatever the vendor, the bastion / session proxy is a hardened Linux system, and the commands below are what you reach for when the GUI cannot tell you why a session failed, a rotation stalled, or a node stopped replicating. This page is a focused, transferable Linux-CLI study guide for that level.

This page teaches the portable Linux skills you need. The vendor-specific commands, exact log paths, service names and CLI tools live in each product's administration guide — each section says what to look up there. New to Linux? Start with Linux essentials for PAM.

Learning objectives¶

Get a shell on a Linux host/appliance and move around safely.
Read and search logs, inspect services/processes/ports, and edit config files.
Call a REST API and parse JavaScript Object Notation (JSON) from the shell.
Recognise the operational commands behind expert-level PAM troubleshooting, REST API automation, and high-availability (HA) operations.

How CLI skills map to PAM operational tasks¶

CLI skill group	PAM operational task it unlocks
Navigate & read files	Finding config, certificates, and recordings on the appliance
Logs & text	Troubleshooting failed sessions, auth errors, proxy crashes
Services & ports	Checking proxy engines, database, API health; verifying listeners
Network & crypto	Diagnosing X.509 / Kerberos / LDAP / RADIUS integrations
REST from shell	Automating account, target and authorization management
Scripting & cron	Password-rotation schedules, batch onboarding, health checks
Services + logs	HA replication and disaster-recovery (DR) operations

flowchart LR
    subgraph CLI["Linux CLI skill groups"]
        Nav["Navigate & read files<br/>ls · cd · less · find"]
        Logs["Logs & text<br/>tail · grep · awk · journalctl"]
        Svc["Services & ports<br/>systemctl · ps · ss"]
        Net["Network & crypto<br/>dig · ping · openssl · ssh-keygen"]
        Api["REST from shell<br/>curl · jq"]
        Auto["Scripting & cron<br/>bash · variables · schedules"]
    end
    Logs --> T1["Troubleshoot sessions<br/>& authentication"]
    Svc --> T1
    Net --> T2["Diagnose auth integrations<br/>(X.509 / Kerberos / LDAP)"]
    Api --> T3["Automate via REST API"]
    Auto --> T4["Password rotation<br/>& scheduled jobs"]
    Svc --> T5["HA & DR<br/>replication"]

1. Getting a shell¶

A PAM bastion is a hardened Linux appliance (usually Debian- or RHEL-based). Expert-level work means connecting to it over Secure Shell (SSH) with the administrative account you've been given, then working at the prompt.

ssh admin@bastion.example.com        # connect (use the account/port you were provided)
whoami                               # which user am I?
id                                   # my user id and groups
pwd                                  # where am I in the filesystem?
exit                                 # leave the session

The exact administrative account, console behaviour, and management ports are appliance-specific — check the vendor's deployment guide, and see PAM reference architecture for the generic component layout. Always prefer read-only inspection first, and take a snapshot before changes.

2. Navigate & read files¶

ls -lah /var/log            # list, long + human sizes + hidden
cd /var/log                 # change directory
less bigfile.log            # page through (q to quit, / to search, G end, g top)
cat file                    # dump small file
find / -name "*.conf" 2>/dev/null   # locate files by name (errors hidden)
stat file                   # size, owner, timestamps

File permissions matter for config and key files (covered in Linux essentials → permissions): chmod, chown, and the rwx triplets.

3. Logs & text processing — the heart of troubleshooting¶

Most troubleshooting is reading logs fast:

tail -f /var/log/app.log              # follow a log live (Ctrl-C to stop)
tail -n 200 app.log                   # last 200 lines
grep -i "error" app.log               # case-insensitive search
grep -ri "kerberos" /var/log/         # recursive search in a tree
zgrep "fail" app.log.1.gz             # search inside rotated/compressed logs
awk '{print $1, $9}' access.log       # pick columns
cut -d: -f1 /etc/passwd                # split on a delimiter
sort | uniq -c | sort -rn              # count & rank (e.g. top error lines)
journalctl -u <service> --since today # systemd journal for one unit

Which logs and databases to read on a given appliance — exact paths and what each contains — are vendor-specific; find them in the product's administration guide. What to look for (failed sessions, authentication errors, anomalous privileged activity) is covered in detection engineering.

4. Services, processes & ports¶

systemctl status <service>            # is it running? recent log lines
systemctl restart <service>           # restart a unit (with care)
ps aux | grep <name>                  # find a running process
top    # or: htop                     # live CPU/memory view
ss -tlnp                              # listening TCP ports + owning process
ss -tn state established              # current connections

A PAM appliance's internal services (database, the RDP and SSH proxy engines, REST API, schedulers, etc.) and their roles are documented per product; the generic component layout is in PAM reference architecture.

5. Text editing config files¶

You'll need at least one terminal editor. vi/vim is everywhere:

vi file.conf      open
  i               insert mode (type)
  Esc             back to command mode
  :w              save        :q  quit        :wq save+quit       :q!  quit no-save
  /text           search

nano is simpler if available (Ctrl-O save, Ctrl-X exit). Back up before editing: cp file.conf file.conf.bak.

6. The REST API from the shell¶

PAM REST API automation is practiced with curl (make requests) and jq (read JSON):

# generic shape — authenticate, then GET a resource, pretty-print the JSON
curl -s -k -H "X-Auth-Key: <api-key>" \
     https://bastion.example.com/api/<resource> | jq .

# common flags:  -s silent  -k skip TLS check (lab only)  -X method  -H header  -d body  -i show headers

Each product's actual authentication headers, resources, methods and response codes are in its API reference — use those exact values, not the placeholder above.

7. Network & crypto helpers — advanced authentication¶

Diagnosing X.509, Kerberos, RADIUS and SAML problems is much easier from the shell:

ping host                     # reachability
dig host  # or: nslookup host # DNS resolution (matters for Kerberos!)
ss -tn                        # who am I connected to?
openssl s_client -connect host:443        # inspect a TLS service + its cert chain
openssl x509 -in cert.pem -noout -text     # decode a certificate (issuer, dates, SAN)
ssh-keygen -lf key.pub                      # fingerprint an SSH key
date                          # clock skew breaks Kerberos — check the time

Background on these protocols: networking & protocols and cryptography & PKI; the wire-level mechanics are in ../protocols/kerberos.md, ../protocols/ldap.md, ../protocols/radius.md and ../protocols/saml.md.

8. Scheduling & light scripting¶

# cron timing: minute hour day-of-month month day-of-week  (used for password-rotation schedules)
# example - run a job at 02:30 every day:
# 30 2 * * *  /path/to/job

# minimal bash:
for h in web db app; do echo "checking $h"; ssh "$h" uptime; done
command && echo OK || echo FAILED      # exit-code branching ($? holds the last code)

Password-rotation scheduling uses cron-style timing — see the vaulting and rotation controls in PAM playbook. Application-launch scripting on Windows targets (AutoIt-style automation) is not bash, but the same automation mindset applies.

9. High availability / operations¶

HA replication (database replication between nodes, often over an SSH tunnel) and the vendor's replication control tool are operated from the shell. Don't memorise invented flags — the exact commands, modes and "what is/isn't replicated" are in the product's HA guide; the design goals are in PAM reference architecture. At the CLI you'll mostly use systemctl, ss, log-reading, and the documented replication command.

Quick-reference¶

Task	Commands
Move around	`ls -lah` · `cd` · `pwd` · `less` · `find`
Read logs	`tail -f` · `grep -ri` · `zgrep` · `journalctl -u`
Services/ports	`systemctl status` · `ps aux` · `ss -tlnp`
Edit config	`vi` / `nano` · back up with `cp` first
REST API	`curl -H` … `\| jq .`
Network/crypto	`dig` · `openssl s_client` · `openssl x509` · `date`
Automate	`cron` timing · `for` loops · `&&` / `\|\|` / `$?`

Safety first¶

You're often on a production security appliance. Inspect read-only before you change anything, snapshot/back up first, avoid destructive commands (rm -rf, redirection over files) unless you're certain, and only act within your authorised scope.

Sources¶

Linux command behaviour: standard GNU coreutils / man pages and Linux essentials for PAM.
PAM reference architecture and control set: this repo's pam-architecture.md and pam-playbook.md.
OpenSSL s_client / x509 manual pages: https://docs.openssl.org/master/man1/openssl-s_client/
curl manual: https://curl.se/docs/manpage.html · jq manual: https://jqlang.github.io/jq/manual/