To reproduce:

* Install fresh Fedora 34 VM
* Compile Bitcoin Core and run `./test/functional/p2p_dns_seeds.py`
break;
    case SyscallSandboxPolicy::VALIDATION_SCRIPT_CHECK: 
        break;
    case SyscallSandboxPolicy::SHUTOFF: 
        seccomp_policy_builder.AllowFileSystem();
        break;
    }
    const SyscallSandboxAction default_action = g_syscall_sandbox_log_violation_before_terminating ? SyscallSandboxAction::INVOKE_SIGNAL_HANDLER : SyscallSandboxAction::KILL_PROCESS;
    std::vector<sock_filter> filter = seccomp_policy_builder.BuildFilter(default_action);
    const sock_fprog prog = {
        .len = static_cast<uint16_t>(filter.size()),
        .filter = filter.data(),
    };
    
    
    
    if (prctl(PR_SET_NO_NEW_PRIVS, 1, 0, 0, 0) != 0) {
        throw std::runtime_error("Syscall sandbox enforcement failed: prctl(PR_SET_NO_NEW_PRIVS)");
    }
    
    
    
    if (prctl(PR_SET_SECCOMP, SECCOMP_MODE_FILTER, &prog) != 0) {
        throw std::runtime_error("Syscall sandbox enforcement failed: prctl(PR_SET_SECCOMP)");
    }
    const std::string thread_name = !util::ThreadGetInternalName().empty() ? util::ThreadGetInternalName() : "*unnamed*";
    LogPrint(BCLog::UTIL, "Syscall filter installed for thread \"%s\"\n", thread_name);
#endif 
}