iptables_lib.js is a test library file containing various functions that can be used to enable and disable firewalls on Linux via the iptables utility.

Previously, ldap_mongos_health_checking.js and ldap_mongos_health_checker_crash.js used these library functions to utilize a firewall. That approach caused numerous BFs as the firewalls affected other, concurrently-running tests on the same host. The tests no longer rely on this library, but it still exists.

We should remove the library entirely as enabling/disabling firewalls within JSTests is unsafe and not recommended due to its impact on other tests.