🟡 Medium   ⏱ 5–30 min  Last verified: 19 May 2026
Affected versions: IBM AIX 7.3

📖 ~1 min read

Table of contents
  1. Symptom & Impact
  2. Environment & Reproduction
  3. Root Cause Analysis
  4. Quick Triage
  5. Step-by-Step Diagnosis
  6. Solution – Primary Fix
  7. Solution – Alternative Approaches
  8. Verification & Acceptance Criteria
  9. Rollback Plan
  10. Prevention & Hardening
  11. Related Errors & Cross-Refs
  12. References & Further Reading

Symptom & Impact

openssh login pauses 10-30s before password prompt.

Environment & Reproduction

Newly built AIX LPAR without proper DNS or /etc/hosts entries.

Root Cause Analysis

sshd performs reverse PTR lookup that times out.

Quick Triage

Run ssh -vvv user@host and check for resolving banner delays.

Step-by-Step Diagnosis

Validate netstat -in DNS and /etc/resolv.conf entries.

Illustrative mockup for aix-7.3 — ssh_slow_login_dns_rever_diag
Diagnostic view for ssh-slow-login-dns-reverse — Illustrative mockup — Progressive Robot

Solution – Primary Fix

Set UseDNS no in /etc/ssh/sshd_config and refresh -s sshd.

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Illustrative mockup for aix-7.3 — ssh_slow_login_dns_rever_fix
Remediation steps for ssh-slow-login-dns-reverse — Illustrative mockup — Progressive Robot

Solution – Alternative Approaches

Add client IP/host to /etc/hosts as quick workaround.

Verification & Acceptance Criteria

ssh prompt appears in under 2 seconds.

Rollback Plan

Re-enable UseDNS once DNS is healthy.

Prevention & Hardening

Monitor named/DNS resolvers and document expected RTT.

Linked with GSSAPIAuthentication delays on Kerberos hosts.

Related tutorial: View the step-by-step tutorial for aix-7.3.

View all aix-7.3 tutorials on the Tutorials Hub →

Browse all common problems & solutions on the Tutorials Hub.

References & Further Reading

IBM Docs: openssh on AIX, resolv.conf.

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