Bug ID 1148053: When client SSL profile has "cache-size 0" or "authenticate always", BIG-IP is unable to decrypt client-side traffic when using tcpdump with "--f5 ssl" method

Last Modified: May 24, 2025

Affected Product(s):
BIG-IP LTM(all modules)

Known Affected Versions:
15.1.0, 15.1.0.1, 15.1.0.2, 15.1.0.3, 15.1.0.4, 15.1.0.5, 15.1.1, 15.1.2, 15.1.2.1, 15.1.3, 15.1.3.1, 15.1.4, 15.1.4.1, 15.1.5, 15.1.5.1, 15.1.6, 15.1.6.1, 15.1.7, 15.1.8, 15.1.8.1, 15.1.8.2, 15.1.9, 15.1.9.1, 15.1.10, 15.1.10.2, 15.1.10.3, 15.1.10.4, 15.1.10.5, 15.1.10.6, 16.1.2.2, 16.1.3, 16.1.3.1, 16.1.3.2, 16.1.3.3, 16.1.3.4, 16.1.3.5, 16.1.4, 16.1.4.1, 16.1.4.2, 16.1.4.3, 16.1.5, 16.1.5.1, 16.1.5.2, 17.1.0, 17.1.0.1, 17.1.0.2, 17.1.0.3, 17.1.1, 17.1.1.1, 17.1.1.2, 17.1.1.3, 17.1.1.4, 17.1.2, 17.1.2.1, 17.1.2.2, 17.5.0

Opened: Sep 08, 2022

Severity: 3-Major

Symptoms

When client SSL profile has "cache-size 0" and/or "authenticate always", the SSL functionality fails to include master-secret in the F5 Ethernet Trailers (f5ethtrailer), thus not being able to decrypt client-side traffic.

Impact

The "cache-size 0" and the "authenticate always" options indicate that BIG-IP does not memorize any session, TMM disables session reuse. No renegotiation is provided even it is enabled. No "session ID" should be present during the SSL/TLS handshake.

Conditions

- Client SSL profile has "cache-size 0" - Client SSL profile has "authenticate always"

Workaround

- For "cache-size 0" scenario, use client SSL profile default cache size - For "authenticate always" scenario, use default value of "authenticate once" - if changing config is not desired, iRule decryption method (K12783074) should work normally

Fix Information

None

Behavior Change

Guides & references

K10134038: F5 Bug Tracker Filter Names and Tips